Function Parser

A function parser. Can theoretically evaluate any basic function. Main function is essentially a test case that evaluates f(x) and f'(x)

To-do

• [X] parenthesis support
• [X] clean up output
• [X] substrings
• [X] improve multi-digit parsing support
• [ ] actually parse "correctly"
• [ ] sqrt cosine and other "fun" functions
• [ ] coefficients
• [ ] negatives