simplified marin test for rans3p

[cekees]

I added the test in the 3d/marin3p folder. It depends on erdc/proteus#683 and is in need of several improvements:

• add Context options to marin.py (e.g. he, genMesh, openTop,...)
• add 4 pressure gauges and 4 line gauges to extract data and replace the included pvpython extractMarinHeight.py and extractMarinPressure.py. Since those scripts pull from the xdmf, the extracted data are dependent on the user's selection of output times, and the pararview scripts don't seem to work as-is for rans3p's mixed FEM spaces anyway.
• check and enable the openTop option--right now this is running with closed boundaries
• check that things are OK in parallel and do a grid refinement study comparing to the experimental data, which is included in the *.dat files.

/cc @arnsong @manuel-quezada @wacyyang @westb @Giovanni-Cozzuto-1989 @Pedrohrw