Changes

I am making the loops for the wp3 ta term (using ADG1 PDF) symmetric.
Prior to this, they ran from thermo levels 2 to nzt-2. This change
makes them symmetric by running them from 2 to nzt-1. There are
no degradations to the results as a result of this change. This
change makes it easier to generalize CLUBB's grid for both
ascending and descending grid directions. The results of this change
are BIT_CHANGING.