PR for merging several PRs at once

[slevis-lmwg]

Description of changes

Please see the individual PRs
#2156 #2148 #2233 #2235 #2237 #2044
Summarized in the ChangeLog.

Specific notes

Please see the individual PRs. Summarized in the ChangeLog.

Contributors other than yourself, if any:
Multiple, as listed in the individual PRs and the ChangeLog.

CTSM Issues Fixed (include github issue #):
Closes #2156
Closes #2148
Closes #2233
Closes #2235
Closes #2237
Closes #2044
and fixes the issues listed therein.

Are answers expected to change (and if so in what way)?
Please see the individual PRs. Summarized in the ChangeLog.

Any User Interface Changes (namelist or namelist defaults changes)?
Please see the individual PRs. Summarized in the ChangeLog.

Testing performed:
In progress. I will document in the ChangeLog.

[slevis-lmwg]

Test-suites

All tests have this expected NLCOMP difference:
found extra variable: 'snow_thermal_cond_method'

cheyenne OK
izumi OK, the following PASS/FAILs are expected, though I want to check with @wwieder and/or @ekluzek before I go ahead with the merge:

1114-134952iz_gnu: 12 tests
    PASS ERS_Lm20_Mmpi-serial.1x1_smallvilleIA.I2000Clm50BgcCropQianRs.izumi_gnu.clm-cropMonthlyNoinitial COMPARE_base_rest (UNEXPECTED: expected FAIL)
    FAIL ERS_Lm20_Mmpi-serial.1x1_smallvilleIA.I2000Clm50BgcCropQianRs.izumi_gnu.clm-cropMonthlyNoinitial BASELINE ctsm5.1.dev151: DIFF
 
1114-134952iz_nag: 32 tests
    FAIL SMS_Ld10_D_Mmpi-serial.CLM_USRDAT.I1PtClm51Bgc.izumi_nag.clm-default--clm-NEON-NIWO BASELINE ctsm5.1.dev151: DIFF
    FAIL SMS_Ld10_D_Mmpi-serial.CLM_USRDAT.I1PtClm51Bgc.izumi_nag.clm-NEON-MOAB--clm-PRISM BASELINE ctsm5.1.dev151: DIFF

[slevis-lmwg]

@wwieder showed me the one-line change in #2044 in /cime_config/usermods_dirs/NEON/defaults/shell_commands
that caused the diffs from baseline in the two NEON tests listed above. I reran the two tests without the one-line change and got bfb with baseline, so now this PR is confirmed ready for the merge.

To be clear, we're keeping the one-line change in the merge.