Allow multiple scores per student/day

[Tom Hoffman]

This requires a significant revision to the interface -- basically shifting to a default per-day view with columns for different scores. The parts we'll need to discuss are: a) what does the monthly view look like then; b) do you still get the monthly view by default if you don't need multiple scores? Should we shift to more of the gradebook data model? Make each day/score an activity? Or is this more like CanDo...