Merge branch 'mark-petersen/update_mpas_200817' into next (PR #3776)

Update MPAS-Source: COMPASS and Documentation files

This PRi brings in a new mpas-source submdoule with changes only to the ocean
core. It updates files unrelated to the E3SM forward model, including:
* Move load_compass_env.sh to the ocean dir  (MPAS-Dev/MPAS-Model#618);
* Update ISOMIP+ docs, including tutorial for Ocean0 on LANL IC
  (MPAS-Dev/MPAS-Model#653);
* Fix path to docs in Travis CI  (MPAS-Dev/MPAS-Model#644);
* atmosphere core init changes  (MPAS-Dev/MPAS-Model#637);
* New Mesh: WC14to60kmL60E3SMv2r03  (MPAS-Dev/MPAS-Model#628);
* Fix ISOMIP+ viz scripts  (MPAS-Dev/MPAS-Model#642);
* Add support for custom critical passages and land blockages
  (MPAS-Dev/MPAS-Model#586); and
* New Mesh: WC12to60kmL60E3SMv2r01  (MPAS-Dev/MPAS-Model#555)

[BFB]