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.
I also find it more descriptive than `tr` in `Truncations`, or `pp` in `Pushout`, or the old `hp` in `HProp`, none of which I ever heard any complaints about.