Add fct richards

[cekees]

Mandatory Checklist

Please ensure that the following criteria are met:

• [x] Title of pull request describes the changes/features
• [x] Request at least 2 reviewers
• [x] If new files are being added, the files are no larger than 100kB. Post the file sizes.
• [x] Code coverage did not decrease. If this is a bug fix, a test should cover that bug fix. If a new feature is added, a test should be made to cover that feature.
• [x] New features have appropriate documentation strings (readable by sphinx)
• [x] Contributor has read and agreed with CONTRIBUTING.md and has added themselves to CONTRIBUTORS.md

As a general rule of thumb, try to follow PEP8 guidelines.

Description

[cekees]

@jhcollins here's a summary:

• remove air-water-vv and proteus_tutorial submodules. Not because those are being deprecated but because the main reason for having them as submodules was automated testing, and I think it's better to run the tests on those submodules separately. We might add them back using a test matrix or some other way to allow longer runtimes.
• remove conda os x test because it exceeds the time limit (could re-enable if we can get multiple cpu's)
• numerous updates to tests to ensure they work on linux and mac os x (despite not running on mac for travis)
• multiple changes to Makefile, setup.py, etc. to address changes in python packaging infrastructure
• changes to address Cython package updates. Mainly I switched to use language_level=3 (e.g. strict Python3) uniformly.
• fix deprecated np.int. Should just be int
• updates to PETSc options (naming)
• updates due to Chrono API changes
• FCT support in Richards model
• Some updates to CutFEM support for solid/air/water models

[jhcollins]

I was hoping to run the richards tests. If they pass on your machine then I will approve.

[cekees]

Yes, they run locally and in the Travis tests running on my fork. Thanks for reviewing!

[jhcollins]

On your fork, the air-water-vv was removed so will this make command fail the tests prematurely?

test: air-water-vv check

[cekees]

Thanks, I will fix that in the makefile. I'm pushing the responsibility of testing air-water-vv and proteus_tutorial onto those repos so we can keep testing within limits of open source support in Travis.