Bugfixes for MoorDyn post processing

[RyanDavies19]

Purpose

Minor bug fixes to improve MoorDyn output plotting:

• Bugfix to allow for plotting MoorDyn outputs that include rods using MoorPy.
• Code to check for *** in MoorDyn outputs. This was an old issue with MoorDyn-F that was fixed in openfast_IO MoorDyn compatibility OpenFAST/openfast#2658, but may still be happening for people using older OpenFAST versions.
• Enables the interval input for animateLines, allowing the animation speed to be controlled.

Type of change

What types of change is it?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Animate MoorDyn-F outputs with rods

Checklist

• I have run existing tests which pass locally with my changes
• I have added new tests or examples that prove my fix is effective or that my feature works
• I have added necessary documentation