Use records, not typeclasses, for subuniverses and modalities

I have been working and thinking about these a lot and I've decided that my original idea of using typeclasses was probably not the best way: when there is more than one modality floating around then it's really better to be passing them explicitly.  This PR turns reflective subuniverses and modalities back into records.
Hm; I wanted something short so that it could handle getting passed an explicit argument without becoming unwieldy.  One can always find out that `to` is about reflective subuniverses by saying `About to`...