*  Fixes a warning in windows.

Fixed possible array index-out-of-bounds crash in error reporting.

Reviewed-by: Roberto Raggi

Ideally most of our visitors won't need to make the QML vs JS
distinction. For these cases it'll be handy to be able to access the AST
no matter whether it's a Program or UiProgram.

Changed the QML/JS editor to treat .qs/.js files as JavaScript, and invoke the appropriate parser for it.

Reviewed-by: Christian Kamm