Merge branch 'mark-petersen/mpas/update_framework' into next (PR #3014)

Update mpas framework in mpas-source

This PR brings in minor updates to MPAS framework through a new
mpas-source submodule. The changes include:
* Log file corrections;
* python 3 correction in COMPASS; and
* changes to atmospheric core (not used by E3SM).

[BFB]