Added ability to automatically pack old (gmod12) addon folders

Closes #3
Removed memory stream from writer and renamed RealtimeCommandline
Added wrapper for realtime functionality
Documentation
Switched RealtimeCommandline to use new RealtimeAddon wrapper
Changed GUI to use RealtimeAddon
Put gmod12 addon conversion and legacy create into same method
Put legacy create and gmod12 convert to same Form too

Also changed some small things so Visual Studio no longer shows warnings
Fix renaming form
Reintroduced console-printed warning for pullable exports

Fixed newline in printing internal filename when adding files
Removed the need of reading the whole GMA into memory
Removed reading new added file if it fails whitelist check and added cleanup
Added whitelist check prior reading to legacy operations too
Fixed handling spaces in folder names for cd command
Added file removal by pressing delete
Added shell execution for addon's files
Fix severe bug resulting in stack overflow
Exception rethrow fixes to preserve stacktrace
Merged UpdateMetadata functionality into Main form
Show the dialog for loading other addon while one is unsaved if it's truly unsaved