Changes

This should be BIT_CHANGING, but only because the value of Cx_min should change in the netcdf file. This will not be answer changing.

Change value of Cx_min to match what is in parameters_tunable.F90

Adding flags and parameters to the r8029 backwards compatible lists. These do not change the backwards compatible results, so that we aren't relying on source code default values.

Changing the value of C_invrs_tau_shear from 0.02 to 0.15.
This commit is BIT_CHANGING

Avoiding stats call for variables that are not set when l_diag_Lscale_from_tau is not true.

Adding line to readme because previous commit will be BIT_CHANGING:108f6ea2c8b3d9357cf551b11a85a2d9a4becc47 in the backwards compatibility run since it will prevent NaNs in the .nc files.

Adding script that checks if two nc files contain different output fields, rather than just checking bit-for-bitness between the two. Also making our run_bin_diff script use this new nc comparator instead of linux diff.

Adjusting the value of C_invrs_tau_shear from 0.15 to 0.16 so that
CLUBB (particularly the MC3E case) completes successfully for all
compiler tests.

You might say that this is BIT_CHANGING.

Add l_smooth_Heaviside_tau_wpxp to smooth discontinuity in invrs_tau_wpxp_zm

This option calls subroutine smooth_heaviside_peskin, which implements the smooth Peskin Heaviside function.
The option is turned off for now, and so the results should remain bit for bit.

For #965.