- Added hints + hintmethod
- hintgroup compatible with loncapa spec
- also does hintfn for custom hints (can do answer history)
- GenericResponse -> LoncapaResponse
- moved response type tags into responsetype classes
- capa_problem should use __future__ division
- hints stored in CorrectMap, copied to 'feedback' in SimpleInput for display
- responsetype used to be instantiated multiple times(!) in capa_problem
now it is instantiated once, and stored in self.responders
- responsetypes.GenericResponse restructured; each superclass
show now provide setup_response (and not __init__), and may
provide get_max_score(); general __init__ provided to
clean up superclasses.
