Set original feature as the default behaviour.
NEW FEATURE: Setting per language for which app to use
NEW FEATURE: Setting per language to pass argument(s) to app
NEW FEATURE: Setting per language to open file URL in local web server
NEW FEATURE: Setting per language to use file system path, instead of URI
NEW FEATURE: Setting per language to wait for the opened app to exit before calling the callback
Tested with VS Code v0.10.8 in MS Windows 10 Pro environment.