Switch test runner output filter sed to extended regex (-E)

test/004_missing_option_argument.txt

@@ -2,7 +2,7 @@
 -s
 :INPUT
 :OUTPUT-FILTER
-1s/^.\+: /boxes: /
+1s/^.+?: /boxes: /
 1s/-- s$/-- 's'/
 :EXPECTED-ERROR 1
 boxes: option requires an argument -- 's'

test/065_size_missing_argument.txt

@@ -3,7 +3,7 @@
 :INPUT
 foo
 :OUTPUT-FILTER
-1s/^.\+: /boxes: /
+1s/^.+?: /boxes: /
 1s/-- s$/-- 's'/
 :EXPECTED-ERROR 1
 boxes: option requires an argument -- 's'

test/testrunner.sh

@@ -84,7 +84,7 @@ export BOXES=../boxes-config
 
 cat $testInputFile | $boxesBinary $boxesArgs >$testOutputFile 2>&1
 declare -ir actualReturnCode=$?
-cat $testOutputFile | tr -d '\r' | sed -f $testFilterFile | diff - $testExpectationFile
+cat $testOutputFile | tr -d '\r' | sed -E -f $testFilterFile | diff - $testExpectationFile
 if [ $? -ne 0 ]; then
     >&2 echo "Error in test case: $testCaseFile (top: actual; bottom: expected)"
     exit 5