Add Respawn function for the robot in Gazebo
In order to compress the time lost when simulating the control algorithms in Gazebo, it would be really nice to have a respawn function for the robot, i.e. a way to delete the old instance of the robot and to instantiate a new one. This would enable us not to kill and restart gazebo each time the robot dies (which is pretty common these times), sparing precious minutes. This issue is a place to discuss and find some directions to implement this functionality.