Amended test slightly.
Made strings use Data prototype in grammar.
Added evaluation of subtraction, strings, and identifiers.
Implemented function creation and began implementing calls.
Added more example tests.
Wrote error handling for calls and changed state to use a stack-like scope.
Various grammar fixes.
Wrote code to evaluate call params and slice excess params if necessary.
Fixed incorrect state.top references and implemented function inner scope.
Added simple.shk to test two outputs.
Added Output object in parser and changed function to require block scope.
Got basic function calls working.