Starting code.
Expression Interface Initialize

Constant, Variable, Addition, and Multiplication

Test cases for Expressions

Implemented new Methods: getValue(), getType(), getLeft(), getRight()

Modified Methods: toString(), equals(), hashCode()
Lexer and Differentiate

Problem 2a and 3
With Tests (not all working though)
Differentiator and Lexer, Parser still needs work
Maintained Expression and Fixed Lexer/Parser Rules
Simplify for Addition and Multiplication
Lexer Parser Tests
Listener Updated
Parser Works but needs testing

Differentiation needs work - MATH
Math Left

Work on Differentiation
Finished Working

Notes for revision: could use some simplifying polishing

Also: more test cases for differatiation/parse/apply?
More Test Cases for DifferentiatorTestApply
FINAL
Finalize
Merge branch 'master' of https://github.com/aanojima/Differentiator