Fix issue with c3d marker labels more than 255

[mrrezaie]

Closing #3606

c3d.pointNames() reads all labels.

Testing I've completed

Worked in my test.

CHANGELOG.md (choose one)

• if accepted.

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This change is 

[nickbianco]

Hi @mrrezaie, thanks for contributing a fix! If you have a working test, please consider adding it to testC3DFileAdapter.cpp:

opensim-core/OpenSim/Common/Test/testC3DFileAdapter.cpp

Line 2 in 232b7f9

* OpenSim: testC3DFileAdapter.cpp *

Additionally, based on discussion in #3606, it seems like some additional filtering of the point data returned by c3d.pointNames() will be necessary to ensure that only marker data is returned. The suggestion from @halleysfifthinc seems like a good one:

I mean, I wouldn't call it a workaround, it is a standards compliant extension of C3D capabilities. Regardless, my point was that if it is desired to remove non-marker point data, the the POINT:ANGLES, POINT:POWERS, POINT:FORCES, and POINT:MOMENTS parameters are arrays of strings that give the names of the point data (i.e. items in POINT:LABELS) that are not markers. That would be a simpler approach with fewer assumptions than hard-coding point names that are known™ to be non-markers.