when we arm in guided mode then enter a special guided_wait_takeoff
state. We keep motors suppressed until one of the following happens
1) disarm
2) guided takeoff command
3) change to AUTO with a takeoff waypoint as first nav waypoint
4) change to another mode
while in this state we don't go to throttle unlimited, and will refuse
a change to AUTO mode if the first waypoint is not a takeoff. If we
try to switch to RTL then we will instead use QLAND
This state is needed to cope with the takeoff sequence used by QGC on
common controllers such as the MX16, which do this on a "takeoff"
swipe:
- changes mode to GUIDED
- arms
- changes mode to AUTO