Changes

change loop index to sclr and edsclr for sclr_dim and edsclr_dim (#1173)

Whenever a loop is dimensioned sclr_dim, use sclr as the loop index. Whenever a loop is dimensioned edsclr_dim, use edsclr as the loop index.

Added changes and tested for binary differences with the following flags for the gabls2 case:
l_host_applies_sfc_fluxes=true/false
l_call_pdf_closure_twice=true/false
l_lmm_stepping=true/false
l_explicit_turbulent_adv_wpxp=true/false

See #987.

Ri zm calc5 (#1175)

* Ri_zm calc (Part 5) - Implementing calc_Ri_zm
CLUBB tocket #1145

Cleaning up subroutine compute_Cx_fnc_Richardson
1) In advance_helper_module.F90:
- Removed superfluous inputs
- Added Brunt Väisälä frequency variables, shear_sqd, and Lscale_zm as inputs
- Removed call to calc_brunt_vaisala_freq_sqd
- Removed zt2zm(Lscale)
- Removed calculation and stat_update_var of shear_sqd

2) In advance_clubb_core:
- Added stat_update_var for shear_sqd
- Adjusted call to compute_Cx_fnc_Richardson

3) Renamed netcdf variable `shear_sqd` to `ddzt_umvm_sqd` to keep variable names consistent.