[ahrs] remove AHRS_UPDATE_FW_ESTIMATOR and ins_x_neutrals
[conf] remove ins_neutrals settings from example and test conf
[math] pprz_algebra_float: convert some macros to functions
[math] pprz_algebra_double: convert some macros to functions
[math] pprz_algebra_int: convert some macros to functions
[math] pprz_algebra_int: convert more macros to functions
[math] convert some trig macros to functions
[math] int32_sqrt as function
[test] update test_algebra
[math] add double_quat_vmult, fixes for nps
[modules] wrapper for ublox gps
[math] cleanup

headers, extern C, etc...
[math] algebra_double functions in c file
[math] algebra_float functions in c file
[math] algebra_int functions in c file
[misc] fix natnet2ivy compilation
[math] use math functions in orientation conversion
[math] wgs84_ellipsoid_to_geoid as function
[math] add missing alias
[Lisa/M] [Lisa/MX] Added IMU subsystems.

The Lisa/M and Lisa/MX V2.1 have an integrated Aspirin like IMU. The
orientation of the sensors is bit different than the Aspirin so for
backwards compatibility we need to assign the axis appropriately, to do
that we add IMU subsystem makefiles and one additianal raw sensor data
field assignement.