[dfu] print exception
[supervision] allow launching of external tools with absolute path
[rotorcraft] use horizontal guidance ref by default

Also use the horizontal guidance reference for HOVER mode.
Using the reference can be temporarly disabled via settings.
The reference is then still computed to stay consistent, but not used.
[nps] don't bypass ahrs by default

By default use the result of the normal ahrs estimation,
if you want to bypass that and use the attitude from NPS define NPS_BYPASS_AHRS to TRUE.
[rotorcraft][messages] GUIDANCE_H_INT message
[airframes] update GUIDANCE_H gains for quadrotor example