Added clearTree and parseString
Made clearTreeHelper and fixed a bug

I accidentally put parseInput and clearTree in the private portion of
the package
Made startcalculator and bug fixes
Made evaluateTree return a Long_Float
Calculator now works for valid input

Next: invalid input and parentheses
It will now output errors correctly (I think)

Now, parentheses
It works with parentheses + bug fixes

It should be finished now...
Merge pull request #4 from jacobmedd/Jacob-Branch

Jacob branch