Inline Analytics

  Display of answer distribution graphics inline on the problem page
  for instructors.

  Problem types supported for graphics:
    - MultipleChoiceResponse
    - ChoiceResponse

  Problem types supported for line item display:
    - OptionResponse
    - NumericalResponse
    - StringResponse
    - FormulaResponse
    via setting

Internal review only for now.
Here too.

Actually, I think I'd like this to be an array of dicts(Python)/objects(JS) rather than an array of arrays.  I think the self-documentation property is better than data compactness, especially b/c the data structure is being parsed in JS but is being created here in Python.