Port ocean internal wave test

[cbegeman]

Here we port the internal gravity wave test case from Compass. This is largely a direct port. The only substantive new code is the transect visualization.

Checklist

• [X] User's Guide has been updated
• [X] Developer's Guide has been updated
• [X] API documentation in the Developer's Guide (api.md) has any new or modified class, method and/or functions listed
• [X] Documentation has been built locally and changes look as expected
• [X] Testing comment in the PR documents testing used to verify the changes
• [X] New tests have been added to a test suite

[cbegeman]

Testing

All new tests have been run on chrys with intel, openmpi. The rpe plots are visually identical with the output from Compass.

[cbegeman]

Standard flux-form advection:

VLR:

Example sections plot:

[xylar]

Feel free to merge as soon as you rebase to fix the conflict.

[cbegeman]

@xylar Thank you for the review! I have resolved the merge conflicts.