TODO

   1 1. Move the set operations from mjo-common and mjo-misc into mjo-set.
   2
   3 2. Add a \powerset command, once I decide whether to use \mathcal{P}
   4    or 2^{X} for the notation.
   5
   6 3. Having S^{n} or H^{n} reduce to simply "S" or "H" in the case where
   7    n=1 doesn't make sense.