Instrument visual model

Description:

Using DistanceGrid collision:
Added a driver for the Omni phantom device
Added a mechanical state controller that gathers data from the phantom and updates the position of a representation of the device in the simulation
Added a computation (EnslavementForceFeedback) of the haptic forces
Added VectorSpringForceField && JointSpringForceField to link the movements of the Omni phantom and the instrument

Redo this tutorial with proximity collision