add check that overall throttle level is below the non-takeoff throttle
instead of just checking that it's motors have hit their lower limits
because low limits can also be caused by high yaw rotation requests.
Absolute climb rate requirement reduced to 30cm/s
Made more strict by requiring 50 consecutive iterations where the climb
rate is below +- 40cm/s. Previously it was 50 cumulative.
Removed check of failsafe.radio when clearing the land flag because it
could result in the vehicle taking off if the user picked it up.
This resolves issue #1021 in which LAND mode could descend at the
PILOT_VELZ rate instead of the WPNAV_SPEED_DN
Pilot defined acceleration is used for AltHold, AutoTune , Circle,
Hybrid, Loiter, OF_Loiter and Sport flight modes
Waypoint Nav (ie. AutoPilot) acceleration is used for Auto, Land, RTL
This resolves issue #880 in which if a GPS failsafe occurred while the
vehicle was already in LAND mode, the LAND would continue to be GPS
controlled LAND instead of pilot-controlled LAND
Randy Mackay
Jonathan Challinger
Andrew Tridgell
Ju1ien