Copter: disarm on land even if pilot throttle not zero

default behaviour remains as before, this is an compile time option only
Tools: we don't have AP_NavEKF.h yet
Copter: add support for MAV_CMD_DO_SET_SERVO
Copter: simplify do-set-servo mission command

This potentially changes the servo number that must be supplied if using
an APM1 but it now shares the same logic as arduplane and also adds
protection that the servo is not attached to the motor.
removed debug message from previous commit.
AC_WPNav: accessor for loiter speed
Copter: allow ch6 tuning of loiter speed
HAL_PX4: use eeprom on PX4 FMUv1 as well

this means we no longer store params on SD at all
PX4: enable MTD on FMUv1 as well
AP_HAL: added set_safety_pwm() API
HAL_PX4: implement set_safety_pwm() API

used to set PWM on motors when disarmed
Plane: setup PWM to be used on throttle when safety is safe on PX4
Copter: faster baro calibration when arming

using update_calibration() instead of the full calibrate() cuts
1.5seconds of the arming time
HAL_PX4: be less verbose about disarmed PWM setup
HAL_PX4: more checking of IO results in eeprom driver
PX4: test MTD device on boot

full rwtest on FMUv2, read test on FMUv1
INS: shortened gyro calibration

Removed delays before calibration, reduced number of samples taken,
widened convergence criteria
Copter: Added GCS feedback for save_trim()

Trim save gives no feedback, so I've added a gcs_send_text() call to
print "Trim saved" so the user knows to re-center trims again
AP_HAL: removed unused enable_mask and disable_mask functions
Plane: check both ground and airspeed in autocal test

when the airspeed ratio is far too low we were not raising it as the
airspeed was never getting above the minimum airspeed

Pair-Programmed-With: Jon Challinger
INS: check for good calibration for 10seconds

Shortened gyro calibration commit also halved the total time we would
look for a good gyro calibration.  This restores the total time to 10
seconds.