PEP8: Fixed E225 whitespace around operator in demos.py
PEP8: Fixed E231 missing whitespace after , in demos.py
PEP8: Fixed some more issues in demos.py
PEP8: entropy.py now passes pep8
PEP8: Fixed long line by more concise test for isinstance

Changed long line by using more concise way of testing whether an object
is an instance of a set of classes. That is I changed something like

    isinstance(object, ClassA) or isinstance(object, ClassB)

to something like

    isinstance(object, (ClassA, ClassB))
PEP8: essolve.py now passes pep8
PEP8: expect.py now passes pep8
PEP8: Fixed some issues in floquet.py
PEP8: Fixed E225 missing whitespace around operator in graph.py
PEP8: Fixed E231 missing whitespace after ',' in graph.py