Changes

Updated CLUBB so that adj_low_res_nu (which can be called on its own
or called through calling setup_parameters) no longer uses
momentum_heights and thermodynamic_heights, but rather makes use
of gr%zm and gr%zt, which are always set and available by the
time the calls are made.

Removing begin_height and end_height as outputs from setup_grid. They
are only necessary as local variables inside of setup_grid.