[beta] Fixes for Electron updates, small additions

Additions:

• A small plugin for high-end indent guide highlighting.
  You can even use it with rainbow brackets!
• There is now an option to display project version as an overlay icon in taskbar.
  This is useful if you have similar-named GMS1+GMS2 projects (e.g. like I do with most of my extensions).
  You can also specify custom icon per-project via <project file path>.taskbar-overlay.png
• Added an option for hinting strings as having GML/HLSL/GLSL code inside.
  This can be wonderful if you embed snippets of code inside your game.

Fixes:

• Fixed HLSL having odd keyword highlighting due to keywords appearing in both "keywords" and "functions" files
• Fixed linter having trouble with "new X" syntax.
• Fixed top-level `}` token being incorrectly typed as `lparen` instead of `rparen`.
• Fixed func1(func2(<cursor with no symbols around it>)) showing argument info for func1

Fixes related solely to updating to Electron 7.x:

• Fixed "tab has changes" icon not showing up
• Fixed outline-view overflowing the window
• Fixed application losing focus whenever a message box pops up