add virtual function resetConstraints to deal with collisions.
  add virtual function addConstraintToConfigProjector to deal with gripper
  disable collisions in the ProblemSolver.

Add map of grasp (=pair<gripper,handle>) to disable the collisions between gripper and handle when a grasping constraint is set.

Add function getDeviceNames in robot to get the names of robots and object in the same order than in the configuration.

Add collisions between devices when buildcomposite robot and also deal with the disabled collisions of grippers.