Basic types, generics, function calls, and nested identifiers

Function calls are now parsed, and identifiers can be nested via dots and indices via brackets. I think I’ll have to reuse the same AST node used for function calls for enum fields carrying tuples when used in an expression other than enum itself.

I got a headache thinking about the type system with generics. It probably would’ve been easier if I drew a diagram before trying to implement them into the AST and parser. I got there eventually.

I have yet to add support for tuple and array types outside the AST interface/type definitions. Basic named types and generics are supported and parsed properly.

I should probably move all my type definitions for the AST to a new file so I don’t have to keep scrolling past a couple hundred lines every time I need to reference them.