- 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
- added correctmap.py with CorrectMap class
- messages subsumed into CorrectMap
- response get_score called with old CorrectMap so hints based on history are possible