1. Modified programs according to output of pep8 and pyflakes (except for
   suggestions about line length, spaces around ** operator, and spaces in
   some dictionary definitions).
2. Removed parenthesis from all return statements.
3. Replaced sys.stderr.write()+exit() statments with raise TypeError() and
   raise ValueError() statements.
4. Added descripting docstring at top of each module in ga directory.
5. Modified docstring for MV class explaining that MV wraps expression of
   linear combinations of non-commutative sympy symbols.
6. Add imports to __init__.py to simplify us of ga.
7. Removed all commented out code.