Finish implementing IR parser

[dubiousconst282]

TODOs

• Core
  • Lexer
  • AST and parser
    • Type parser
      • Nested types: Parent+Child
      • Compound types: pointer, array, byref: int*[]&
      • Generic type specs: List`1+Enumerator[int]
  • Materializer (convert ASTs into IR instructions)
  • Missing instructions
    • StoreArray (syntax: may need annotation for element type)
    • Convert
    • Switch (parsing)
    • Intrinsics (see #5)
    • Guard (parsing), Leave/Continue
    • Load/Store PtrInst (syntax: may need annotation for element type)
    • NewObj
    • and others
• Find a way to prevent conflicts with anonymous/sequential names (enforce correctness or don't put them in the SymbolTable?)
• Support for multiple error messages (don't throw exceptions unless necessary)
  • Find a way to prevent cascade errors (maybe skip to the next line?)
• Single pass parser (get rid of the AST/materializer and create IR directly)
• Method declarations
• [?] Type declarations

Known Bugs

• Block order is not preserved during materialization (lazy calls to CreateBlock())

[dubiousconst282]

Closing since the parser is quite complete and implementing missing instructions shouldn't be too complicated.