setBaseFrame sets the relationship between the world and the
  first body in the kinematic configuration.
 
    This method expects a 4x4 homogeneous transform that
    describes the relationship between the world frame and the
    frame of the first body. All kinematics are expressed in
    the world frame. Units of XYZ translation are in [m].
 
    Example
      % Shift the base frame of the kinematics by .5 meters
      % in the +x direction.
      newBaseFrame = eye(4);
      newBaseFrame(1:3,4) = [.5; 0; 0];
      setBaseFrame( newBaseFrame );