Add error message for unmatched types from branches
Add test for different types from branches
Move compiler driver script into package
No longer need to run parser module as a script
Import modules from package root
Move CORE_DIR into runac.util module
Rename variable to prevent shadowing
Use CORE_DIR in code generation
Access Error classes straight from runac.util module
Get CORE_DIR from util module
Resolve opt types from AST
Allow Phi node types to be opt types
Test for opt values being None
Test replacing opt-typed value with normal
Add NoValue/DeOpt nodes inside checked blocks
Don't unwrap opt type for Is comparisons
Handle NoneVal nodes in specialization pass
Handle specialization of Phi nodes in the face of opt types
Handle more node types in pretty printer
Start checking for opt types in places where they're not allowed