PX4: added conversion lib for rotation
PX4: try to startup FMUv3 with right rotations
ph2 support: Fix typo in startup rc
PX4: fixed l3gd20 rotation

based on first flight log
PX4: added comments on FMU3 rotations
AP_Compass: support 3 mags on PX4
Copter: log up to 3 mags
PX4: try to start both hmc5883 sensors

internal + external
Plane: support 3 magnetometers
Rover: support 3 magnetometers
PX4: fixed orientation of internal hmc5883 on FMUv3
GCS_MAVLink: add CMD_NAV_GUIDED to ardupilotmega.xml
GCS_MAVLink: generate after adding CMD_NAV_GUIDED
AP_Mission: add support for MAV_CMD_NAV_GUIDED
Copter: remove mode from guided_set_dest

This duplicate check stopped us from reusing guided
guided_set_destination as part of Auto's nav_guided command
Copter: add nav_guided suport to Auto mode
Copter: accept guided pos updates when doing NAV_GUIDED cmd
Copter: accept condition-yaw commands in guided
GCS_Common: minor typo in comments
GCS_Mavlink: add MAV_CMD_NAV_VELOCITY

This is an earth frame velocity request message