OP-1317 Apadted airspeed calculation from ground speed and orientattion changes: applied extended IMU wind estimation, filtering takes place now with Holt-Winters double exponential smoothing on orientation vector and speed vector, matrix calculation replaced by a direct calculation of the fuselage vector, renamed gps_airspeed into imu_airspeed because estimation relies on imu results and a n estimate of ground speed and not directly a GPS signal
OP-1317 Added two file (actually renames)
OP-1317 Added better comments on the function of the partial calculation of the rotation matrix. And added a remark on the debuging variable in the airspeed object definition
OP-1317 Changed filtering method of IMU airspeed calculation into a Butterworth second order filter
OP-1317 Changed filtering method of IMU airspeed calculation into a Butterworth second order filter
OP-1317 Small optimizations of code, delete of debug variables in airspeed object and uncrustify
OP-1317 Merged with next
Merge branch 'next' into andrecillo/OP-1317_IMU_wind_estimation

Conflicts:
	flight/modules/Airspeed/airspeed.c
OP-1317 Corrected error in calculation of low pass filter cut-off frequencies
OP-1317 Low-pass filter parameters added to airpeedSettings: IMUBasedEstimationLowPassPeriod1 pre-filter period in seconds, IMUBasedEstimationLowPassPeriod2 filter period in seconds. Oscillations with shorter periods than these, are filtered. If airspeed has too much noise increase IMUBasedEstimationLowPassPeriod2, else if it is too smooth descrease it.
OP-1317 Bettered jump treatment in yaw calculation and some cosmetics
Merge branch 'next' into corvuscorax/OP-1317_IMU_wind_estimation
OP-1317 changed imu wind estimation to actually estimate wind (and lowpass filter it)
Merge remote-tracking branch 'origin/corvuscorax/OP-1317_IMU_wind_estimation' into corvuscorax/OP-1317_IMU_wind_estimation
OP-1317 - project 3d airspeed vector unto fuselage vector to get scalar airspeed estimate
OP-1317 changed type and default for airspeedsettings filter coefficients
drive-by bugfix in #ifdefed code affecting simposix
OP-1317 changed int into int32_t in function Quaternion2PY()
OP-1317 merge with branch corvuscorax/OP-1317_IMU_wind_estimation
OP-1317 added a proper initialization of the Butterworth filter values