[ins] IIR filter replacing mean in hff

(Second order Butterworth) implementation for INS subsystem.

closes #677
[ins] hf_float: fix compilation with GPS_LAG
[ins] hf_float: remove inline from functions
[ins] Made it possible to use GPS altitude
[ins] vf_extended: rename update_alt to update_z

this makes more sense as it is with z-down and vff_update_z_conf can be used for both vf_float and vf_extended_float
[ins] no baro update if vf_reset && !baro_initialized
[ins] gps_passthrough type for rotorcrafts
[rotorcraft] simple HITL by using ref as gps
[rotorcraft] gps_sim_hitl: set gps alt and hmsl

now the simple HITL should work with ins gps_passthrough
[modules] cam_roll: CAM_ROLL_START_MODE and remove cam_roll_switch
[chibios] make ringBuffer compile
[modules] meteo_france_DAQ: only print info message once
[modules] sonar_adc: add distance to struct
[ins] trying to fix ins xsens700
Merge remote-tracking branch 'paparazzi/master' into testing_irridium

master sync
° add iridium ground relay agent, only downlink effective
* two way implementation of satcom ground segment.