opendrive: finish off #1026

* Fix errcheck and golint warnings
  * Remove unused constants and fix comments
  * Parse error responses properly
  * Fix Open with RangeOption
  * Fix Move, Copy and DirMove
  * Implement DirCacheFlush
  * Check interfaces are correct
  * Remove debugs and update overview
  * Correct feature flags
  * Pare replacement characters down to the minimum set
  * Add to the integration tests

fstest/test_all/test_all.go

@@ -137,6 +137,11 @@ var (
 			SubDir:   false,
 			FastList: false,
 		},
+		{
+			Name:     "TestOpenDrive:",
+			SubDir:   false,
+			FastList: false,
+		},
 	}
 	// Flags
 	maxTries = flag.Int("maxtries", 5, "Number of times to try each test")