* hbar.tex [rtj]
   - improved the treatment of the ideality factor. Before it was
     included in the Boltzmann factor from statistical mechanics but
     it really has no role there. The role has to do with the details
     of recombination dynamics and how it is controlled by temperature.
     I added a cursory description that gets the right idea across,
     (I think) without getting bogged down in the details.