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.

Okay, NOW correctly handling scope wrt mixins. (If a binding exists then change it, otherwise make a new one in the topmost (i.e., local) environment.)

Extensible environments. More powerful than necessary, but will be necessary if scoped variables and mixins are added to the language.

Basic mixin functionality. Still need to properly implement environment lookup and correct indentation.