Now JSLint is checking the code.
Evaluation of script now handles var defs and set!
Variables defined can now be used in assignments and definitions.
Some simple predefined functions can now be called.
Refactored predefined functions so they all are defined in a single object.
This way calls can be made by looking up the appropriate name.
Lambdas can now be called.
Environment is modified globaly with 'a' and 'b' on call to function.
Refactored code to more easily be able to change the underlying representation from the parser.