Added automatic discovery of gmod12 structure to addon creation

Fixed a bug in parsing string delimiter quotes from info.txt files.
Commented out some more currently unused metadata stuff
Added writing info.txt to extract methods
Fixed optional parameter default resulting in no compile
Fixed showing right-click options enabled
Initial commit for cross-platform (Mono) support.

Needed to remove the P/Invoke because there's no kernel32.dll on Mono.
But unfortunately, the application crashes at the export functionality's
pull notification (FileSystemWatcher.Changed) event.
Fixed GDI+ null reference on application close
Fixed Mono crashing on multicast delegates for FileWatch
Fixed Main disabling itself on Mono and not using platform-specific path separator
Added properly handling file overwrite prompt for exports
Fixed collection modifying itself from a foreach