Changes

Adding expldiff budget terms for thlm and rtm (#1252)

* Adding expldiff budget terms for thlm and rtm

* Removing unintentional line.

* Fixing initialization-to-zero problem

* Adding some comments.

* Adding thlm_ed and rtm_ed to standard_stats.in

* Adding thlm_ed and rtm_ed to all_stats.in

* Fixing two bugs. Budget balance test passes and results are b4b.

This commit is BIT_CHANGING, but only because it adds additional
stats fields to the _zt.nc files. Answers would only change if
l_do_expldiff_rtm_thlm=T.