Haxe in Haxe - WIP

Attempt at rewriting the haxe compiler directly in haxe.

The parser is a slightly modified version of haxeparser: https://github.com/Simn/haxeparser

Based on haxe commit b3cc1d79495acafa0ceabc985cd663efc00a28a5

Using ImmutableList introduced on https://github.com/HaxeFoundation/haxe/tree/genml