Diff files: Fixed issue #385
ExecuteCommand: Now supports arguments
LESS source map: Nested .map file under css file
JSHint: Handle parse failures for ignore regex

Cache parsed regexes for performance.
Skip blank items.

Should fix #386
JSHint: Show error for invalid regex in Options
Merge pull request #388 from SLaks/jshint-ignore-fixes

Handle invalid regexes for JSHint Ignore list