- RC+RefCell pattern used... everywhere
- Ast type implemented
- unit tests for func_call
- more changes, but this commit scope has grown significantly and I
cannot list them all
- added vars to lib
- fixed adders and getters to both vtable and ftable
- made function operations a dual type (enum)
- prototyped calling of stored external ASTs with
arguments (additional operation type
- stub for eval
- added index function to Cell
