Add logging; cleanup reset and start
Add logging; cleanup reset and start

Add logging to send_message_to_exec(), cmd_callback()
Remove _state_start() and _state_reset() mode and arm change.

ProgrammingRobotsStudyGroup/robo_magellan,ProgrammingRobotsStudyGroup/robo_magellan,ProgrammingRobotsStudyGroup/robo_magellan,ProgrammingRobotsStudyGroup/robo_magellan