How to set goal_threshold to allow small motions

[rr-dave]

Problem description:

• Send motoman a trajectory where all final joint values are within 0.01 radians (the default goal threshold) of the start joint values.
• This could be a significant cartesian motion, eg s joint at 1.5m reach: 1.5 x sin(0.01) = 15mm
• The trajectory is not sent to the robot because of the check here

  motoman/motoman_driver/src/industrial_robot_client/joint_trajectory_action.cpp

  Line 337 in 433be15

  if (withinGoalConstraints(last_trajectory_state_map_[group_number],

I've previously experimented with changing the goal threshold and seen values less than 0.001 seem to time out, I suspect due to the joint 4 discrepancies identified in #592. Do you have any suggestions for how to make short trajectories execute? I'm considering trying to make only the initial check use a much tighter tolerance and leave the checks in controllerStateCB as they are.

[rr-dave]

This may be a duplicate of #467