AP_TECS : Reduce tendency to overspeed during climbout

The old code relies on the action of the integrator to raise the nose above the minimum pitch angle which depending on the model and the tuning can be too slow to correct. Biasing the pitch angle to climbout minimum will reduce the taken before an overspeed condition is corrected.
SITL: added SIM_RC_FAIL

simulate RC failure with no signal
HAL_SITL: use SIM_RC_FAIL
Plane: allow throttle failsafe on no RC input

on PX4 we just stop getting input on loss of RC - we need to consider
this to be "throttle failsafe"
Plane: only allow right rudder for arming

copter users may try to use left rudder to ensure aircraft is
disarmed. Making left rudder arm could be dangerous