BehaviourTree tracking

[DingoOz]

It would be cool to see the "thinking" of the robot via it's BT in realtime.

[CDonosoK]

That it's quite interesting, I will think on how I can display the BT and which type of library is the most common used for this, as well the type of message. Maybe I will jsut implement a custom one using the astroviz_interfaces package.