[export] fix datalink export (missing file)
[MF_DAQ] update and fix mf_daq module

- use telemetry message
- fix datalink event
- protection for memcpy max size
[gcs] fix AGL display in edit waypoint box

also fix a strange bug where set_adjustment function doesn't correctly
display the actual initial value (but it was correctly set, only display
was 0.)
[sonar] sonar system using ABI interface

- unified interface for sonar (sonar_adc was broken with latest commit
  for ardrone)
- median filter removed from ins_int, implement in sonar drivers if
  needed
- compiles but not tested yet
[ins] remove obsolete ins update functions on baro and sonar
[sonar] fix some sonar related issues
[ardrone2][baro] optional median filter on baro

some crazy values can remain, it seems that they are well filtered using
this median filter
[makefile] AHRS frequency flags where missing for ardrone2