diff --git a/README.md b/README.md
index 1a38e3c..cdf60a7 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ If you're on Windows, use the open source telnet client [PuTTY](https://www.chia
 
 ### With npm
 
-If you haven't already got Node.js >= version 4.5, then [go get it](http://nodejs.org/).
+If you haven't already got Node.js >= version 8.12, then [go get it](http://nodejs.org/).
 
 ```
 npm install -g mapscii
diff --git a/package-lock.json b/package-lock.json
index 809a984..d87e34f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,7 +14,7 @@
       "resolved": "https://registry.npmjs.org/@mapbox/vector-tile/-/vector-tile-1.3.0.tgz",
       "integrity": "sha1-xJX5clJb78zvzYOPRf+jfvO3D+g=",
       "requires": {
-        "@mapbox/point-geometry": "0.1.0"
+        "@mapbox/point-geometry": "~0.1.0"
       }
     },
     "acorn": {
@@ -29,7 +29,7 @@
       "integrity": "sha1-r9+UiPsezvyDSPb7IvRk4ypYs2s=",
       "dev": true,
       "requires": {
-        "acorn": "3.3.0"
+        "acorn": "^3.0.4"
       },
       "dependencies": {
         "acorn": {
@@ -46,10 +46,10 @@
       "integrity": "sha1-c7Xuyj+rZT49P5Qis0GtQiBdyWU=",
       "dev": true,
       "requires": {
-        "co": "4.6.0",
-        "fast-deep-equal": "1.0.0",
-        "fast-json-stable-stringify": "2.0.0",
-        "json-schema-traverse": "0.3.1"
+        "co": "^4.6.0",
+        "fast-deep-equal": "^1.0.0",
+        "fast-json-stable-stringify": "^2.0.0",
+        "json-schema-traverse": "^0.3.0"
       }
     },
     "ajv-keywords": {
@@ -81,7 +81,7 @@
       "integrity": "sha1-c9g7wmP4bpf4zE9rrhsOkKfSLIY=",
       "dev": true,
       "requires": {
-        "sprintf-js": "1.0.3"
+        "sprintf-js": "~1.0.2"
       }
     },
     "array-union": {
@@ -90,7 +90,7 @@
       "integrity": "sha1-mjRBDk9OPaI96jdb5b5w8kd47Dk=",
       "dev": true,
       "requires": {
-        "array-uniq": "1.0.3"
+        "array-uniq": "^1.0.1"
       }
     },
     "array-uniq": {
@@ -111,9 +111,9 @@
       "integrity": "sha1-Y/1D99weO7fONZR9uP42mj9Yx0s=",
       "dev": true,
       "requires": {
-        "chalk": "1.1.3",
-        "esutils": "2.0.2",
-        "js-tokens": "3.0.2"
+        "chalk": "^1.1.3",
+        "esutils": "^2.0.2",
+        "js-tokens": "^3.0.2"
       },
       "dependencies": {
         "ansi-regex": {
@@ -128,11 +128,11 @@
           "integrity": "sha1-qBFcVeSnAv5NFQq9OHKCKn4J/Jg=",
           "dev": true,
           "requires": {
-            "ansi-styles": "2.2.1",
-            "escape-string-regexp": "1.0.5",
-            "has-ansi": "2.0.0",
-            "strip-ansi": "3.0.1",
-            "supports-color": "2.0.0"
+            "ansi-styles": "^2.2.1",
+            "escape-string-regexp": "^1.0.2",
+            "has-ansi": "^2.0.0",
+            "strip-ansi": "^3.0.0",
+            "supports-color": "^2.0.0"
           }
         },
         "strip-ansi": {
@@ -141,7 +141,7 @@
           "integrity": "sha1-ajhfuIU9lS1f8F0Oiq+UJ43GPc8=",
           "dev": true,
           "requires": {
-            "ansi-regex": "2.1.1"
+            "ansi-regex": "^2.0.0"
           }
         }
       }
@@ -163,7 +163,7 @@
       "integrity": "sha1-wHshHHyVLsH479Uad+8NHTmQopI=",
       "dev": true,
       "requires": {
-        "balanced-match": "1.0.0",
+        "balanced-match": "^1.0.0",
         "concat-map": "0.0.1"
       }
     },
@@ -178,7 +178,7 @@
       "integrity": "sha1-lAhe9jWB7NPaqSREqP6U6CV3dR8=",
       "dev": true,
       "requires": {
-        "callsites": "0.2.0"
+        "callsites": "^0.2.0"
       }
     },
     "callsites": {
@@ -193,9 +193,9 @@
       "integrity": "sha512-Az5zJR2CBujap2rqXGaJKaPHyJ0IrUimvYNX+ncCy8PJP4ltOGTrHUIo097ZaL2zMeKYpiCdqDvS6zdrTFok3Q==",
       "dev": true,
       "requires": {
-        "ansi-styles": "3.2.0",
-        "escape-string-regexp": "1.0.5",
-        "supports-color": "4.5.0"
+        "ansi-styles": "^3.1.0",
+        "escape-string-regexp": "^1.0.5",
+        "supports-color": "^4.0.0"
       },
       "dependencies": {
         "ansi-styles": {
@@ -204,7 +204,7 @@
           "integrity": "sha512-NnSOmMEYtVR2JVMIGTzynRkkaxtiq1xnFBcdQD/DnNCYPoEPsVJhM98BDyaoNOQIi7p4okdi3E27eN7GQbsUug==",
           "dev": true,
           "requires": {
-            "color-convert": "1.9.1"
+            "color-convert": "^1.9.0"
           }
         },
         "supports-color": {
@@ -213,7 +213,7 @@
           "integrity": "sha1-vnoN5ITexcXN34s9WRJQRJEvY1s=",
           "dev": true,
           "requires": {
-            "has-flag": "2.0.0"
+            "has-flag": "^2.0.0"
           }
         }
       }
@@ -236,7 +236,7 @@
       "integrity": "sha1-s12sN2R5+sw+lHR9QdDQ9SOP/LU=",
       "dev": true,
       "requires": {
-        "restore-cursor": "2.0.0"
+        "restore-cursor": "^2.0.0"
       }
     },
     "cli-width": {
@@ -257,7 +257,7 @@
       "integrity": "sha512-mjGanIiwQJskCC18rPR6OmrZ6fm2Lc7PeGFYwCmy5J34wC6F1PzdGL6xeMfmgicfYcNLGuVFA3WzXtIDCQSZxQ==",
       "dev": true,
       "requires": {
-        "color-name": "1.1.3"
+        "color-name": "^1.1.1"
       }
     },
     "color-name": {
@@ -278,9 +278,9 @@
       "integrity": "sha1-CqxmL9Ur54lk1VMvaUeE5wEQrPc=",
       "dev": true,
       "requires": {
-        "inherits": "2.0.3",
-        "readable-stream": "2.3.3",
-        "typedarray": "0.0.6"
+        "inherits": "^2.0.3",
+        "readable-stream": "^2.2.2",
+        "typedarray": "^0.0.6"
       }
     },
     "core-util-is": {
@@ -295,9 +295,9 @@
       "integrity": "sha1-6L0O/uWPz/b4+UUQoKVUu/ojVEk=",
       "dev": true,
       "requires": {
-        "lru-cache": "4.1.1",
-        "shebang-command": "1.2.0",
-        "which": "1.3.0"
+        "lru-cache": "^4.0.1",
+        "shebang-command": "^1.2.0",
+        "which": "^1.2.9"
       }
     },
     "debug": {
@@ -321,13 +321,13 @@
       "integrity": "sha1-wSyYHQZ4RshLyvhiz/kw2Qf/0ag=",
       "dev": true,
       "requires": {
-        "globby": "5.0.0",
-        "is-path-cwd": "1.0.0",
-        "is-path-in-cwd": "1.0.0",
-        "object-assign": "4.1.1",
-        "pify": "2.3.0",
-        "pinkie-promise": "2.0.1",
-        "rimraf": "2.6.2"
+        "globby": "^5.0.0",
+        "is-path-cwd": "^1.0.0",
+        "is-path-in-cwd": "^1.0.0",
+        "object-assign": "^4.0.1",
+        "pify": "^2.0.0",
+        "pinkie-promise": "^2.0.0",
+        "rimraf": "^2.2.8"
       }
     },
     "doctrine": {
@@ -336,7 +336,7 @@
       "integrity": "sha512-y0tm5Pq6ywp3qSTZ1vPgVdAnbDEoeoc5wlOHXoY1c4Wug/a7JvqHIl7BTvwodaHmejWkK/9dSb3sCYfyo/om8A==",
       "dev": true,
       "requires": {
-        "esutils": "2.0.2"
+        "esutils": "^2.0.2"
       }
     },
     "earcut": {
@@ -349,7 +349,7 @@
       "resolved": "https://registry.npmjs.org/encoding/-/encoding-0.1.12.tgz",
       "integrity": "sha1-U4tm8+5izRq1HsMjgp0flIDHS+s=",
       "requires": {
-        "iconv-lite": "0.4.18"
+        "iconv-lite": "~0.4.13"
       }
     },
     "escape-string-regexp": {
@@ -364,43 +364,43 @@
       "integrity": "sha512-UCJVV50RtLHYzBp1DZ8CMPtRSg4iVZvjgO9IJHIKyWU/AnJVjtdRikoUPLB29n5pzMB7TnsLQWf0V6VUJfoPfw==",
       "dev": true,
       "requires": {
-        "ajv": "5.5.2",
-        "babel-code-frame": "6.26.0",
-        "chalk": "2.3.0",
-        "concat-stream": "1.6.0",
-        "cross-spawn": "5.1.0",
-        "debug": "3.1.0",
-        "doctrine": "2.0.2",
-        "eslint-scope": "3.7.1",
-        "espree": "3.5.2",
-        "esquery": "1.0.0",
-        "estraverse": "4.2.0",
-        "esutils": "2.0.2",
-        "file-entry-cache": "2.0.0",
-        "functional-red-black-tree": "1.0.1",
-        "glob": "7.1.2",
-        "globals": "11.1.0",
-        "ignore": "3.3.7",
-        "imurmurhash": "0.1.4",
-        "inquirer": "3.3.0",
-        "is-resolvable": "1.0.1",
-        "js-yaml": "3.10.0",
-        "json-stable-stringify-without-jsonify": "1.0.1",
-        "levn": "0.3.0",
-        "lodash": "4.17.4",
-        "minimatch": "3.0.4",
-        "mkdirp": "0.5.1",
-        "natural-compare": "1.4.0",
-        "optionator": "0.8.2",
-        "path-is-inside": "1.0.2",
-        "pluralize": "7.0.0",
-        "progress": "2.0.0",
-        "require-uncached": "1.0.3",
-        "semver": "5.4.1",
-        "strip-ansi": "4.0.0",
-        "strip-json-comments": "2.0.1",
-        "table": "4.0.2",
-        "text-table": "0.2.0"
+        "ajv": "^5.3.0",
+        "babel-code-frame": "^6.22.0",
+        "chalk": "^2.1.0",
+        "concat-stream": "^1.6.0",
+        "cross-spawn": "^5.1.0",
+        "debug": "^3.0.1",
+        "doctrine": "^2.0.2",
+        "eslint-scope": "^3.7.1",
+        "espree": "^3.5.2",
+        "esquery": "^1.0.0",
+        "estraverse": "^4.2.0",
+        "esutils": "^2.0.2",
+        "file-entry-cache": "^2.0.0",
+        "functional-red-black-tree": "^1.0.1",
+        "glob": "^7.1.2",
+        "globals": "^11.0.1",
+        "ignore": "^3.3.3",
+        "imurmurhash": "^0.1.4",
+        "inquirer": "^3.0.6",
+        "is-resolvable": "^1.0.0",
+        "js-yaml": "^3.9.1",
+        "json-stable-stringify-without-jsonify": "^1.0.1",
+        "levn": "^0.3.0",
+        "lodash": "^4.17.4",
+        "minimatch": "^3.0.2",
+        "mkdirp": "^0.5.1",
+        "natural-compare": "^1.4.0",
+        "optionator": "^0.8.2",
+        "path-is-inside": "^1.0.2",
+        "pluralize": "^7.0.0",
+        "progress": "^2.0.0",
+        "require-uncached": "^1.0.3",
+        "semver": "^5.3.0",
+        "strip-ansi": "^4.0.0",
+        "strip-json-comments": "~2.0.1",
+        "table": "^4.0.1",
+        "text-table": "~0.2.0"
       }
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     "eslint-scope": {
@@ -409,8 +409,8 @@
       "integrity": "sha1-PWPD7f2gLgbgGkUq2IyqzHzctug=",
       "dev": true,
       "requires": {
-        "esrecurse": "4.2.0",
-        "estraverse": "4.2.0"
+        "esrecurse": "^4.1.0",
+        "estraverse": "^4.1.1"
       }
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     "espree": {
@@ -419,8 +419,8 @@
       "integrity": "sha512-sadKeYwaR/aJ3stC2CdvgXu1T16TdYN+qwCpcWbMnGJ8s0zNWemzrvb2GbD4OhmJ/fwpJjudThAlLobGbWZbCQ==",
       "dev": true,
       "requires": {
-        "acorn": "5.2.1",
-        "acorn-jsx": "3.0.1"
+        "acorn": "^5.2.1",
+        "acorn-jsx": "^3.0.0"
       }
     },
     "esprima": {
@@ -435,7 +435,7 @@
       "integrity": "sha1-z7qLV9f7qT8XKYqKAGoEzaE9gPo=",
       "dev": true,
       "requires": {
-        "estraverse": "4.2.0"
+        "estraverse": "^4.0.0"
       }
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     "esrecurse": {
@@ -444,8 +444,8 @@
       "integrity": "sha1-+pVo2Y04I/mkHZHpAtyrnqblsWM=",
       "dev": true,
       "requires": {
-        "estraverse": "4.2.0",
-        "object-assign": "4.1.1"
+        "estraverse": "^4.1.0",
+        "object-assign": "^4.0.1"
       }
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@@ -466,9 +466,9 @@
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       "dev": true,
       "requires": {
-        "chardet": "0.4.2",
-        "iconv-lite": "0.4.18",
-        "tmp": "0.0.33"
+        "chardet": "^0.4.0",
+        "iconv-lite": "^0.4.17",
+        "tmp": "^0.0.33"
       }
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     "fast-deep-equal": {
@@ -495,7 +495,7 @@
       "integrity": "sha1-OrGi0qYsi/tDGgyUy3l6L84nyWI=",
       "dev": true,
       "requires": {
-        "escape-string-regexp": "1.0.5"
+        "escape-string-regexp": "^1.0.5"
       }
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     "file-entry-cache": {
@@ -504,8 +504,8 @@
       "integrity": "sha1-w5KZDD5oR4PYOLjISkXYoEhFg2E=",
       "dev": true,
       "requires": {
-        "flat-cache": "1.3.0",
-        "object-assign": "4.1.1"
+        "flat-cache": "^1.2.1",
+        "object-assign": "^4.0.1"
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@@ -514,10 +514,10 @@
       "integrity": "sha1-0wMLMrOBVPTjt+nHCfSQ9++XxIE=",
       "dev": true,
       "requires": {
-        "circular-json": "0.3.3",
-        "del": "2.2.2",
-        "graceful-fs": "4.1.11",
-        "write": "0.2.1"
+        "circular-json": "^0.3.1",
+        "del": "^2.0.2",
+        "graceful-fs": "^4.1.2",
+        "write": "^0.2.1"
       }
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@@ -538,12 +538,12 @@
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       "dev": true,
       "requires": {
-        "fs.realpath": "1.0.0",
-        "inflight": "1.0.6",
-        "inherits": "2.0.3",
-        "minimatch": "3.0.4",
-        "once": "1.4.0",
-        "path-is-absolute": "1.0.1"
+        "fs.realpath": "^1.0.0",
+        "inflight": "^1.0.4",
+        "inherits": "2",
+        "minimatch": "^3.0.4",
+        "once": "^1.3.0",
+        "path-is-absolute": "^1.0.0"
       }
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@@ -558,12 +558,12 @@
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       "dev": true,
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-        "array-union": "1.0.2",
-        "arrify": "1.0.1",
-        "glob": "7.1.2",
-        "object-assign": "4.1.1",
-        "pify": "2.3.0",
-        "pinkie-promise": "2.0.1"
+        "array-union": "^1.0.1",
+        "arrify": "^1.0.0",
+        "glob": "^7.0.3",
+        "object-assign": "^4.0.1",
+        "pify": "^2.0.0",
+        "pinkie-promise": "^2.0.0"
       }
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     "graceful-fs": {
@@ -578,7 +578,7 @@
       "integrity": "sha1-NPUEnOHs3ysGSa8+8k5F7TVBbZE=",
       "dev": true,
       "requires": {
-        "ansi-regex": "2.1.1"
+        "ansi-regex": "^2.0.0"
       },
       "dependencies": {
         "ansi-regex": {
@@ -623,8 +623,8 @@
       "integrity": "sha1-Sb1jMdfQLQwJvJEKEHW6gWW1bfk=",
       "dev": true,
       "requires": {
-        "once": "1.4.0",
-        "wrappy": "1.0.2"
+        "once": "^1.3.0",
+        "wrappy": "1"
       }
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@@ -639,20 +639,20 @@
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       "dev": true,
       "requires": {
-        "ansi-escapes": "3.0.0",
-        "chalk": "2.3.0",
-        "cli-cursor": "2.1.0",
-        "cli-width": "2.2.0",
-        "external-editor": "2.1.0",
-        "figures": "2.0.0",
-        "lodash": "4.17.4",
+        "ansi-escapes": "^3.0.0",
+        "chalk": "^2.0.0",
+        "cli-cursor": "^2.1.0",
+        "cli-width": "^2.0.0",
+        "external-editor": "^2.0.4",
+        "figures": "^2.0.0",
+        "lodash": "^4.3.0",
         "mute-stream": "0.0.7",
-        "run-async": "2.3.0",
-        "rx-lite": "4.0.8",
-        "rx-lite-aggregates": "4.0.8",
-        "string-width": "2.1.1",
-        "strip-ansi": "4.0.0",
-        "through": "2.3.8"
+        "run-async": "^2.2.0",
+        "rx-lite": "^4.0.8",
+        "rx-lite-aggregates": "^4.0.8",
+        "string-width": "^2.1.0",
+        "strip-ansi": "^4.0.0",
+        "through": "^2.3.6"
       }
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@@ -672,7 +672,7 @@
       "integrity": "sha1-ZHdYK4IU1gI0YJRWcAO+ip6sBNw=",
       "dev": true,
       "requires": {
-        "is-path-inside": "1.0.1"
+        "is-path-inside": "^1.0.0"
       }
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     "is-path-inside": {
@@ -681,7 +681,7 @@
       "integrity": "sha1-jvW33lBDej/cprToZe96pVy0gDY=",
       "dev": true,
       "requires": {
-        "path-is-inside": "1.0.2"
+        "path-is-inside": "^1.0.1"
       }
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@@ -725,8 +725,8 @@
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       "dev": true,
       "requires": {
-        "argparse": "1.0.9",
-        "esprima": "4.0.0"
+        "argparse": "^1.0.7",
+        "esprima": "^4.0.0"
       }
     },
     "json-schema-traverse": {
@@ -752,8 +752,8 @@
       "integrity": "sha1-OwmSTt+fCDwEkP3UwLxEIeBHZO4=",
       "dev": true,
       "requires": {
-        "prelude-ls": "1.1.2",
-        "type-check": "0.3.2"
+        "prelude-ls": "~1.1.2",
+        "type-check": "~0.3.2"
       }
     },
     "lodash": {
@@ -768,8 +768,8 @@
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       "dev": true,
       "requires": {
-        "pseudomap": "1.0.2",
-        "yallist": "2.1.2"
+        "pseudomap": "^1.0.2",
+        "yallist": "^2.1.2"
       }
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@@ -784,7 +784,7 @@
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       "dev": true,
       "requires": {
-        "brace-expansion": "1.1.8"
+        "brace-expansion": "^1.1.7"
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@@ -825,8 +825,8 @@
       "resolved": "https://registry.npmjs.org/node-fetch/-/node-fetch-1.7.3.tgz",
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       "requires": {
-        "encoding": "0.1.12",
-        "is-stream": "1.1.0"
+        "encoding": "^0.1.11",
+        "is-stream": "^1.0.1"
       }
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@@ -841,7 +841,7 @@
       "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
       "dev": true,
       "requires": {
-        "wrappy": "1.0.2"
+        "wrappy": "1"
       }
     },
     "onetime": {
@@ -850,7 +850,7 @@
       "integrity": "sha1-BnQoIw/WdEOyeUsiu6UotoZ5YtQ=",
       "dev": true,
       "requires": {
-        "mimic-fn": "1.1.0"
+        "mimic-fn": "^1.0.0"
       }
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     "optionator": {
@@ -859,12 +859,12 @@
       "integrity": "sha1-NkxeQJ0/TWMB1sC0wFu6UBgK62Q=",
       "dev": true,
       "requires": {
-        "deep-is": "0.1.3",
-        "fast-levenshtein": "2.0.6",
-        "levn": "0.3.0",
-        "prelude-ls": "1.1.2",
-        "type-check": "0.3.2",
-        "wordwrap": "1.0.0"
+        "deep-is": "~0.1.3",
+        "fast-levenshtein": "~2.0.4",
+        "levn": "~0.3.0",
+        "prelude-ls": "~1.1.2",
+        "type-check": "~0.3.2",
+        "wordwrap": "~1.0.0"
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@@ -890,8 +890,8 @@
       "resolved": "https://registry.npmjs.org/pbf/-/pbf-3.1.0.tgz",
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       "requires": {
-        "ieee754": "1.1.8",
-        "resolve-protobuf-schema": "2.0.0"
+        "ieee754": "^1.1.6",
+        "resolve-protobuf-schema": "^2.0.0"
       }
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     "pify": {
@@ -912,7 +912,7 @@
       "integrity": "sha1-ITXW36ejWMBprJsXh3YogihFD/o=",
       "dev": true,
       "requires": {
-        "pinkie": "2.0.4"
+        "pinkie": "^2.0.0"
       }
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@@ -960,7 +960,7 @@
       "resolved": "https://registry.npmjs.org/rbush/-/rbush-2.0.1.tgz",
       "integrity": "sha1-TPrKKMMGS8DudUMaG3mZDode76k=",
       "requires": {
-        "quickselect": "1.0.0"
+        "quickselect": "^1.0.0"
       }
     },
     "readable-stream": {
@@ -969,13 +969,13 @@
       "integrity": "sha512-m+qzzcn7KUxEmd1gMbchF+Y2eIUbieUaxkWtptyHywrX0rE8QEYqPC07Vuy4Wm32/xE16NcdBctb8S0Xe/5IeQ==",
       "dev": true,
       "requires": {
-        "core-util-is": "1.0.2",
-        "inherits": "2.0.3",
-        "isarray": "1.0.0",
-        "process-nextick-args": "1.0.7",
-        "safe-buffer": "5.1.1",
-        "string_decoder": "1.0.3",
-        "util-deprecate": "1.0.2"
+        "core-util-is": "~1.0.0",
+        "inherits": "~2.0.3",
+        "isarray": "~1.0.0",
+        "process-nextick-args": "~1.0.6",
+        "safe-buffer": "~5.1.1",
+        "string_decoder": "~1.0.3",
+        "util-deprecate": "~1.0.1"
       }
     },
     "require-uncached": {
@@ -984,8 +984,8 @@
       "integrity": "sha1-Tg1W1slmL9MeQwEcS5WqSZVUIdM=",
       "dev": true,
       "requires": {
-        "caller-path": "0.1.0",
-        "resolve-from": "1.0.1"
+        "caller-path": "^0.1.0",
+        "resolve-from": "^1.0.0"
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@@ -999,7 +999,7 @@
       "resolved": "https://registry.npmjs.org/resolve-protobuf-schema/-/resolve-protobuf-schema-2.0.0.tgz",
       "integrity": "sha1-5nsGKmfwLRG9aIbnDv2niEB+D7Q=",
       "requires": {
-        "protocol-buffers-schema": "2.2.0"
+        "protocol-buffers-schema": "^2.0.2"
       }
     },
     "restore-cursor": {
@@ -1008,8 +1008,8 @@
       "integrity": "sha1-n37ih/gv0ybU/RYpI9YhKe7g368=",
       "dev": true,
       "requires": {
-        "onetime": "2.0.1",
-        "signal-exit": "3.0.2"
+        "onetime": "^2.0.0",
+        "signal-exit": "^3.0.2"
       }
     },
     "rimraf": {
@@ -1018,7 +1018,7 @@
       "integrity": "sha512-lreewLK/BlghmxtfH36YYVg1i8IAce4TI7oao75I1g245+6BctqTVQiBP3YUJ9C6DQOXJmkYR9X9fCLtCOJc5w==",
       "dev": true,
       "requires": {
-        "glob": "7.1.2"
+        "glob": "^7.0.5"
       }
     },
     "run-async": {
@@ -1027,7 +1027,7 @@
       "integrity": "sha1-A3GrSuC91yDUFm19/aZP96RFpsA=",
       "dev": true,
       "requires": {
-        "is-promise": "2.1.0"
+        "is-promise": "^2.1.0"
       }
     },
     "rx-lite": {
@@ -1042,7 +1042,7 @@
       "integrity": "sha1-dTuHqJoRyVRnxKwWJsTvxOBcZ74=",
       "dev": true,
       "requires": {
-        "rx-lite": "4.0.8"
+        "rx-lite": "*"
       }
     },
     "safe-buffer": {
@@ -1063,7 +1063,7 @@
       "integrity": "sha1-RKrGW2lbAzmJaMOfNj/uXer98eo=",
       "dev": true,
       "requires": {
-        "shebang-regex": "1.0.0"
+        "shebang-regex": "^1.0.0"
       }
     },
     "shebang-regex": {
@@ -1089,7 +1089,7 @@
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       "dev": true,
       "requires": {
-        "is-fullwidth-code-point": "2.0.0"
+        "is-fullwidth-code-point": "^2.0.0"
       }
     },
     "sprintf-js": {
@@ -1103,8 +1103,8 @@
       "resolved": "https://registry.npmjs.org/string-width/-/string-width-2.1.1.tgz",
       "integrity": "sha512-nOqH59deCq9SRHlxq1Aw85Jnt4w6KvLKqWVik6oA9ZklXLNIOlqg4F2yrT1MVaTjAqvVwdfeZ7w7aCvJD7ugkw==",
       "requires": {
-        "is-fullwidth-code-point": "2.0.0",
-        "strip-ansi": "4.0.0"
+        "is-fullwidth-code-point": "^2.0.0",
+        "strip-ansi": "^4.0.0"
       }
     },
     "string_decoder": {
@@ -1113,7 +1113,7 @@
       "integrity": "sha512-4AH6Z5fzNNBcH+6XDMfA/BTt87skxqJlO0lAh3Dker5zThcAxG6mKz+iGu308UKoPPQ8Dcqx/4JhujzltRa+hQ==",
       "dev": true,
       "requires": {
-        "safe-buffer": "5.1.1"
+        "safe-buffer": "~5.1.0"
       }
     },
     "strip-ansi": {
@@ -1121,7 +1121,7 @@
       "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-4.0.0.tgz",
       "integrity": "sha1-qEeQIusaw2iocTibY1JixQXuNo8=",
       "requires": {
-        "ansi-regex": "3.0.0"
+        "ansi-regex": "^3.0.0"
       }
     },
     "strip-json-comments": {
@@ -1142,12 +1142,12 @@
       "integrity": "sha512-UUkEAPdSGxtRpiV9ozJ5cMTtYiqz7Ni1OGqLXRCynrvzdtR1p+cfOWe2RJLwvUG8hNanaSRjecIqwOjqeatDsA==",
       "dev": true,
       "requires": {
-        "ajv": "5.5.2",
-        "ajv-keywords": "2.1.1",
-        "chalk": "2.3.0",
-        "lodash": "4.17.4",
+        "ajv": "^5.2.3",
+        "ajv-keywords": "^2.1.0",
+        "chalk": "^2.1.0",
+        "lodash": "^4.17.4",
         "slice-ansi": "1.0.0",
-        "string-width": "2.1.1"
+        "string-width": "^2.1.1"
       }
     },
     "term-mouse": {
@@ -1173,7 +1173,7 @@
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       "dev": true,
       "requires": {
-        "os-tmpdir": "1.0.2"
+        "os-tmpdir": "~1.0.2"
       }
     },
     "type-check": {
@@ -1182,7 +1182,7 @@
       "integrity": "sha1-WITKtRLPHTVeP7eE8wgEsrUg23I=",
       "dev": true,
       "requires": {
-        "prelude-ls": "1.1.2"
+        "prelude-ls": "~1.1.2"
       }
     },
     "typedarray": {
@@ -1208,7 +1208,7 @@
       "integrity": "sha512-xcJpopdamTuY5duC/KnTTNBraPK54YwpenP4lzxU8H91GudWpFv38u0CKjclE1Wi2EH2EDz5LRcHcKbCIzqGyg==",
       "dev": true,
       "requires": {
-        "isexe": "2.0.0"
+        "isexe": "^2.0.0"
       }
     },
     "wordwrap": {
@@ -1229,7 +1229,7 @@
       "integrity": "sha1-X8A4KOJkzqP+kUVUdvejxWbLB1c=",
       "dev": true,
       "requires": {
-        "mkdirp": "0.5.1"
+        "mkdirp": "^0.5.1"
       }
     },
     "x256": {
diff --git a/package.json b/package.json
index 819adfd..541eaa6 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "mapscii": "./bin/mapscii.sh"
   },
   "engines": {
-    "node": ">=4.5.0"
+    "node": ">=8.12.0"
   },
   "keywords": [
     "map",