ROS node for MultiWii / Cleanflight flight controllers

This ROS nodes uses the MultiWii Serial Protocol (MSP) to communicate with MultiWii and Cleanflight based flight controllers.

It reuses many of the mavros message definitions and topics and is therefore compatible to some visualisation and control nodes (e.g. joystick teleoperation) that are part of the mavros_extras package. The current implementation supports control over RC channels or direct motor access (active DYNBALANCE), arming/disarming by a service and it publishes IMU values and current RC/motor states.