MBD: Add setters/getters and fix visu of mooring lines

[tridelat]

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

• Adds essential getters and setters that are independent of Chrono syntax (as the latter is subject to change as Chrono is updated), for robustness/convenience
• Fixes visualization issue of mooring lines with Paraview
• Adds a small test for getters/setters
• Also fixes an issue with WaveTools introduced in #1141

[codecov[bot]]

Codecov Report

Merging #1144 into master will increase coverage by 0.13%. The diff coverage is 96.00%.

@@            Coverage Diff             @@
##           master    #1144      +/-   ##
==========================================
+ Coverage   51.63%   51.76%   +0.13%     
==========================================
  Files         539      540       +1     
  Lines      102272   103395    +1123     
==========================================
+ Hits        52806    53524     +718     
- Misses      49466    49871     +405     

Impacted Files	Coverage Δ
proteus/WaveTools.py	0.00% <0.00%> (ø)
proteus/tests/test_mbd_chrono.py	100.00% <100.00%> (ø)
proteus/tests/griffiths_lane_6/sm_gl_6_3d_n.py	94.73% <0.00%> (-5.27%)	:arrow_down:
proteus/tests/griffiths_lane_6/sm_gl_6_3d_p.py	71.87% <0.00%> (-0.74%)	:arrow_down:
proteus/tests/test_boundaryconditions.py	97.33% <0.00%> (-0.25%)	:arrow_down:
proteus/config/copper.py	0.00% <0.00%> (ø)
proteus/mprans/RANS3PSed.py	0.00% <0.00%> (ø)
proteus/tests/FSI/floatingCube.py	100.00% <0.00%> (ø)
proteus/tests/TwoPhaseFlow/damBreak_PUMI.py	92.59% <0.00%> (ø)
... and 9 more

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