[ins] trying to fix ins xsens700
[rotorcraft] CAUTION! ref_quat scaling fix

Attitude reference quaternion:
Fix scale of angle in 2nd order model, since error quaternion contains the half-angles we get 2*omega^2*err

This means that you should halve your REF_OMEGA_[PQR] parameters to get nearly the same as before.
[conf] rotorcrafts: update REF_OMEGA_x in examples

to half the value than before
[rotorcraft] ref_quat_int: omega, zeta accessors and settings
[rotorcraft] ref_quat_float: omega accessors and settings
[conf] settings: fix typos in stabilization_att_float_quat
[tools] gen_modules_doc: update wiki url
[dox][mcu_periph] document some more stuff
update excludes in Doxyfile

and prevent copied chibios file to add doxygen groups
[airborne] remove unused agl and alt_vfilter

alt_vfilter is basically the same as ins/vf_float
[server] add airspeed data in FLIGHT_PARAM message
[server] send negative value if no airspeed available

on a second thought it is safer to tell that there is no airspeed data,
ground speed is already available in the message anyway
[server] change again airspeed field position

for compatibility with PPRZonDroid beta version
[rotorcraft] rc setpoint handling refactored

closes #684 which partially solves #599
[mission] add support for global coordinates in mission module
[ext] update libopencm3
[stm32] update libopencm3 includes

don't explicitly include f1 headers, rather just the generic stm32 ones which will then include the correct ones depending on which familiy is defined
[ext] update luftboot to get libopencm3 include fixes
[rotorcraft] add a HOME mode

similar to HOME mode in fixedwing firmware.
[rotorcraft] go to FAILSAFE mode after 1.5*MAX_DIST_FROM_HOME

In failsafe the rotorcraft should perform a landing which makes more sense than KILL.
You can still set KILL_AS_FAILSAFE to kill instead.