Added the path modules test files

Added the path modules test files

Added the new path modules test file. This replaces the old
helpers_test.go file.

The currently failing tests are:
TestReplaceExtension
TestFilename
TestFileAndExt
TestGuessSection
TestFindCWD
TestWriteToDisk

In addition the TestSafeWriteToDisk test case is currently disabled.
It will panic if enabled.

In addition there are some minor changes to path.go. They are:
Refactored MakePathToLower to simplify it.
Commented out, pending removal, Sanitize as it appears to be unused.
Fixed the resource leak in UnicodeSanitize

Conflicts:
	helpers/path.go