TODO

* pointers
* operator precedence
* enum
* interactive mode
* casts
* change heap to use a single consistent freelist node struct
* periodic heap cleanup
* fix type comparison to take into account array size
* expression and auto-cast support for all types
* octal/hex character constants
* fix #include
* eliminate host puts use
* move all system specific includes to a single file

Need test/debug:
* all break/continue variations
* #define

Also:
* Remove Var parameter from HeapPopStack() once we're certain it all works