Improving semantic syntax highlighting

[YellowAfterlife]

There is currently a bunch of small issues related to GMEdit not being actively aware of nested functions:

• with disables semantic highlighting for implicit self variables (fn() vs self.fn()) for the entire top-level function
• Multi-level local variables are shared across the top-level function
• Outline-view only knows top-level and sub-top-level functions - no nesting

The root cause for all of these is that GMEdit does not have knowledge of nested scopes through the file - it only notes down top-level scopes (see: GmlScopes) and then another level in outline-view.

Addressing this requires rewriting a good chunk of syntax highlighting to store nested context data (chain of names along with ending curly bracket depths) inside AceGmlState.

Caveats include

with (some) a += b
    + c

being pretty much impossible to highlight correctly without even broader rewrites to make syntax highlighter aware of current code context.