[beta] A web-based version and type system improvements

Additions

• There is now a web-based version of GMEdit!
  This can be handy for viewing/editing GameMaker projects without having/being able to install software on the device.

Improvements

• Anton has further refined font and sprite editors!
• There is now a linter flag to allow implicit nullable->non-nullable (T? to T) casts.
  This can be convenient if you set your values to undefined a lot.
• I added options for specifying default window size and/or native window border.
  (native window border can be good on Mac if you are slightly annoyed by right-aligned Windows-style control buttons on GMEdit’s window)

Type system

• Functions can now be implicitly cast to script type.
• You can now use either<A;B> instead of (A|B)
  (because GMS2 IDE has a hard time handling parentheses in argument names/types)
• You can now do globalvar a, b, c; /// @is {type} to mark all of them as the same type
  (note: declarations must be on the same line)
• method(value, function(){...}) is now handled as a special case so that self inside function will be the type of value.
• Linter now warns about missing fields when accessing anonymous struct literals ({...}).
• real can now be used as an alias to number.
• Assigning undefined to a variable no longer sets its type to undefined with inference enabled
• Trying to cast a value to the same type that it is now shows a warning.
• Fixed wrong return types in a few more functions.

Fixes

• Fixed 2.2 rename failing if you have a tab without a path open (e.g. search)
• Fixed a few cases where words/numbers were highlighted incorrectly when next to a : or inside ?:
• Fixed warning line markers not playing well with code folding.
• Added a warning when trying to use GMEdit with an incompatible Electron version.
• Fixed “No idea how to open -psn#” on Mac for real this time.
• Fixed new X(); not being allowed by linter.
• Fixed try{}catch(e) not adding e to local variables.
• Fixed GML files inside GMS2 extensions sometimes getting indexed multiple times.
• Fixed projects sometimes not indexing right when opening a ZIP/YYZ.