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_TECS : Added flight mode for maximum range
Plane : Added parameter and code to enable maximum range mode to be selected
Plane : Added code to inhibit max range speed mode when circling a waypoint
AP_TECS : Added 5sec time constant low-pass filter to max range airspeed demand
Plane : Added parameter and code to enable maximum range mode to be selected