Verification of ft sensing for manipulator force feedback.

[bsb808]

Testing PR #16 raises some questions about the validity of the torque sensor plugin outputs and their use for force feedback. See the video: https://vimeo.com/422977387 There seem to be some simulation artifacts.

Can we test a subset of joints by adding external forces to gain confidence that they are providing trustworthy results?

A suggested step is to simplify the example from the PR to a standalone manipulator on a fixed pedestal with no ocean world (just empty gazebo world). This would simplify the testing and allow us to do some sniff tests of the outputs.

[bsb808]

At this point, this is not on our list of active efforts. We are leaving the issue open, but not actively working on it at this time.

[crvogt]

Closing, see #167