Initial commit. Added one needed method.
Arithmatic parser + ground work for abstract scoring.
Fleshing out the Scorer, Score, ScoreProvider, and associated subclasses.
Added basic JsScorer class to score based on JavaScript scripts.
Math evaluator now supports full variable names instead of single characters.
Added Rhino dependency (js.jar) for JavaScript evaluation.
Other sundry changes to Score, ProblemScore, etc.