Add for an while loops
Interpreter uses references, not boxes
Ensure args are freed
Add if, logical operators

Use Rc for everything!
Add variables, environments.

TODO, assignments
Add initial statement parsing/interpretation
Fix dumb bug

Less and Greater were backwards in the lexer
Add basic Interpreter
Add Expression data enum
Add Literal Enum.

There are only so many types of literals.
Exit with error on failure
Initial commit of lox tree walking interpreter, in rust