Implement MassSpringRepresentation::applyDofCorrection

- applyDofCorrection updates the representation's velocity and position
- Added error checking for whenever state is updated (after applying DOF correction,
after calculating the next time step in free motion)
- Implemented unit testing for ApplyDofCorrection
Merge branch 'feature/massSpring-applyDofCorrection' into 'master'

Implement mass-spring applyDofCorrection

+1: Vien Tran, Paul Novotny, Harald Scheirich

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/621553