* [swarm] add formation control for rotorcraft
Based on Ewoud Smeur (INDI) and Hector Garcia de Marina (Formation
control) work. See
https://blog.paparazziuav.org/2017/12/02/pilot-a-super-rotorcraft
- several UAV can be control from the ground (using a joystick for
instance) by sending proper acceleration setpoint to the INDI guidance
controller
- configuration of the formation is done from a JSON file (2 example
files provided)
Some extra changes:
- update accel from IMU in GPS passthrough INS
- add accel setpoint to ABI messages
- by to accel setpoint in INDI guidance
- send ground reference from natnet2ivy
- possibility to have a joystick labeled 'GCS' with input2ivy
Gautier Hattenberger