(not) Using RobotWrapper in Crocoddyl

I believe that it would be a good procedure not using robot wrapper in the lib, but for loading and display. When loading a robot wrapper, we should get the robot model "rmodel = robot.model", and create a new data (do not use the one of robot wrapper, keep it for display). Then do not pass robotwrapper to your methods and classes, but directly pass rmodel. We might keep robotwrapper in the loggerdisplay yet.