Implemented parsing. INT and SUM parsing (arity 4) does not currently
work. Cleaned up some more code. Implemented the open parenthesis as the
identity function, allowed me to make major simplifications in the
parsing loop.

Change-Id: I9d1e9b578baa78575ebaf235deff4ccfef66ca06
Signed-off-by: qaovxtazypdl <qaovxtazypdl@hotmail.com>