Generate joint_limits.yaml using ordered joints

[davetcoleman]

The std::sort structure was storing pointers, so I believe it was populating its binary search trees based on memory address locations, I've added a custom comparator that instead compares the joint model's names, ensureing alphabetical ordering.

Fix for https://github.com/ros-planning/moveit_setup_assistant/issues/53

[isucan]

+1

[hersh]

I just ran this and the joints in joint_limits.yaml were still not in alphabetical order. Does this work for you?

[hersh]

oop, hold on, ran with wrong ROS_PACKAGE_PATH...

[hersh]

ok, works fine. :)