Remove unused source files.

- The NimbleThread use is removed when the NimbleScaffold derived from
  BasicThread.
Revise LabJack unit test to expose a bug in LabJackScaffold

No matter there is an output producer set on a LabJack device or not,
the LabJack device should work.

With this revision, it exposed a bug in LabJackScaffold that when an
output producer is set on a LabJack device but not providing any initial
output, input consumers of this LabJack won't get any input.
Fix a bug in LabJackScaffold

A LabJack device should be updated no matter if there is an output
producer or not.
Remove FemRepresentationParameters, not being used

FemRepresentationParameters appears to be not used anymore but is still
hanging around. The parameters have long since been moved to the
OdeState and the FemRepresentation. This change just removes it.
Merge branch 'fix/remove-femrepresentationparameters' into 'master'

Remove FemRepresentationParameters, not being used

+1: haizhouW, Julien Lenoir, Ryan Beasley

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1278823
Fix cpplint warnings in Graphics::OsgSkeletonRepresentation
Merge branch 'fix/cpplintWarningGfxOsgSkeletonRep' into 'master'

Fix cpplint warnings in Gfx::OsgSkeletonRepresentation

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1282963
Merge remote-tracking branch 'origin/master' into fix/labjackscaffold
Merge branch 'fix/labjackscaffold' into 'master'

Fix a bug in LabJackScaffold

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1282453
Merge branch 'fix/fix-nimble-cpplint' into 'master'

Nimble: Remove unused source files.

+1: Paul Novotny, Ryan Beasley, haizhouW

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1262673