initial milestone4 upload
Initial tree class
safety commit
restructuring the driver
restructure tree printing
access tree data correctly in print
Make file added
Fixed a bug with how S goes to expr
Fixup of the tree library
Added tree to the parser
change the way the tree is printed adn allow for print prefix and
postfix notation
print tree at the end of parse
Add infix notation printing of the tree.

fixes #11
testing out infix notation printing