Add indices to FollowJointTrajectory to store trajectory index being executed (#67)

Author: Levi-Armstrong

control_msgs/action/FollowJointTrajectory.action

@@ -54,8 +54,12 @@ string[] joint_names
 trajectory_msgs/JointTrajectoryPoint desired
 trajectory_msgs/JointTrajectoryPoint actual
 trajectory_msgs/JointTrajectoryPoint error
+# the currently used point from trajectory.points array
+int32 index
 
 string[] multi_dof_joint_names
 trajectory_msgs/MultiDOFJointTrajectoryPoint multi_dof_desired
 trajectory_msgs/MultiDOFJointTrajectoryPoint multi_dof_actual
 trajectory_msgs/MultiDOFJointTrajectoryPoint multi_dof_error
+# the currently used point from multi_dof_trajectory.points array
+int32 multi_dof_index