Faster loading speed and better precision for LBTF

Low Bandwidth Trajectory Follower has now much less comments
and debugging information - which means that it will parse on UR robot
in around 400 ms instead of 700 ms. It also has an adjustment loop
in case the robot does not reach any of the trajectory points specified.

It will catch-up at every trajectory point sent by MoveIt and will try
to get as close as possible to the desired pointi (it will check if all
joints are within MAX_JOINT_DIFFERENCE from the desired positions)

include/ur_modern_driver/ros/lowbandwidth_trajectory_follower.h

@@ -22,7 +22,7 @@ private:
   URServer server_;
 
   double time_interval_, servoj_time_, servoj_time_waiting_, max_waiting_time_, \
-         servoj_gain_, servoj_lookahead_time_;
+         servoj_gain_, servoj_lookahead_time_, max_joint_difference_;
   bool debug_, more_debug_;
 
   std::string program_;