New compiler pipeline

[Astavie]

We're doing too much at once right now.

Idea for the new pipeline:

1. Tokens
2. AST
3. AST + Semantic Analysis
   • the AST is kept as is, maybe with package information removed
   • identifiers are linked to their definitions
4. Typed Polymorphic IR
   • type-checking while the AST is converted to an IR format
5. Monomorphized IR
   • remove polymorphism and effects