In Joint sliders make the trajectory publisher not latching

[toliver]

Make the trajectory publisher not latching, (and probably the rest of the publishers as well).

Test thoroughly for good behaviour. The idea of using latched publishers was to avoid losing command messages, which sometimes seemed to cause jerky behaviour. We should test if that is still happening.

The reason to make them non-latching is that when we go to teach mode, and move the robot to another position, when we go back to trajectory mode, the sliders are still in their old position, and as the publisher is latched, the command is sent again to the trajectory controllers when they start again. This can cause unexpected and potentially dangerous movements.