Copter: disable some aux channels on hexa and octas

Resolves issue #324
RC_Channel: formatting
Copter: rc10, rc11 available even without MOUNT
Copter: default Ch7 to DO_NOTHING

Ch7/Ch8 Save_WP feature triggers when switch is brought high (instead of
low) to be consistent with other aux features
Copter: more Ch7/Ch8 event logging

Additional event logging for SaveWP, Fence, Acro trainer, Save Trim
Copter: recalc distance to home during arming

fixes an rare edge case in which the fence could trigger immediately
after arming
Copter: disable autotune if pilot moves yaw stick
Copter: arming check that throttle is above failsafe
Copter: int gyros on arm, not on first boot

this makes first boot much faster
PX4: changed startup to fail if no px4io on FMUv2
Plane: faster startup

make it less likely to send wrong INS_PRODUCT_ID, plus don't waste as
much time
AP_InertialSensor: SITL doesn't use Oilpan code any more
Plane: added altitude and ground speed to NTUN logs
AP_Airspeed : Fixes bug that caused airspeed calibration to be sent a zero airspeed

This bug resulted in the airspeed ratio going to the maximum value of 4 and staying there. This could lead to a very slow flying model and a stall.
Plane: fixed PM message
Rover: fixed PM message
Plane: mark 2.76beta1
InertialNav: added get_velocity_xy
Copter: TOY mode updates
Copter: remove unused Toy param