Fixes for auto takeoff and safety

Reduced failsafe tilt to 50 degrees
Added make tilt for auto takeoff of 0.05 radians
Made height limit work for all modes
Failsafe bug fix

Fixed issue where throttle control stops working on initiation of
failsafe. Current implementation decends at max speed on failsafe for
10 seconds and then cuts props. This should be good for flying up to 15
meters high.