[rotorcraft] v_adapt: limit min/max estimated hover throttle

The adaptive vertical filter estimates the ratio of vertical acceleration over thrust command.
In effect this will now limit the throttle applied in hover between 20% and 75% of max throttle by default.
[fixedwing] additonals for energy ctrl

better handling for engine out and max_acc can be set in airframe
closes #497
[modules] fix to use amsys airspeed for control
[modules] a little airspeed_amsys cleanup
[mcu_periph] replace gpio_output_[high|low] with gpio_[set|clear]

That means using the already existing gpio_set and gpio_clear from libopencm3 for stm32.
And defining these for the lpc.
set paparazzi_version to v5.1_devel
[modules] angle of attack sensor fix and cleanup
[dox] update comment in state inteface
improve paparazzi_version if git tags are not found
Merge pull request #498 from flixr/gpio_setclear

[mcu_periph] replace gpio_output_[high|low] with gpio_[set|clear]
KroozSD imu driver improvements

Fixed magnetometer axes.
Accel median filter disabled by default.

closes #501
[STM32] Very limited simple SPI1 slave driver

closes #500
[rotorcraft] v_adapt: reset while not in_flight
[math] brackets for macro arguments...
[ahrs] remove some unneeded vars in float_mlkf
[ahrs] geo mag for float ahrs
[math] untabify
[rotorcraft] v_adapt: config improvements and refactor

- GUIDANCE_V_ADAPT_INITIAL_HOVER_THROTTLE settable in % with default of 0.3
- GUIDANCE_V_ADAPT_THROTTLE_ENABLED:
  - TRUE by default if GUIDANCE_V_NOMINAL_HOVER_THROTTLE was not defined
  - FALSE by default if only GUIDANCE_V_NOMINAL_HOVER_THROTTLE was set in airframe file
    (for backwards compatibily)
- switching between nominal_trottle and the adaptive estimate during operation via settings
[conf] update some airframe examples to GUIDANCE_V_ADAPT changes
[cleaning] remove some f***ing names and comments