Piling up the builtin function tests in here. Will move it to the spec when everything is implemented.

Allowing builtin functions to be overloaded based on number of parameters. Don't know if it's worth it because only one function appears to need this.

Built-in function framework is in place. Had to jump through some hoops to resolve the usual #include dependency headaches.

Environments now store a link to the global env. Makes it easy to handle 2-level scope for mixins and arbitrarily nested scopes for variables.

Trying out a different comment scanning method in anticipation of implementing the comment formatting routine.