[Makefile] improve detection of lablgtk2-gnome.*
[rotorcraft] Add forward mode for transitioning vehicles
[rotorcraft] TRANSITION_MAX_OFFSET in radians, float fixes
[Makefile] use -fPIC for all architectures
[umarim] remove warning if no mag are used with umarim
[tcas] tcas always runs on AP. Proposed solution for compile error.
[Makefile] find correct lablgtk2 init
[paparazzicenter] also check PRINT_CONFIG for upload button
[Makefile] ground_segment.opt target to build native gcs/server
[rotorcraft] fix FAILSAFE vertical setpoint

This was a regression, thx Michal for catching this!!
The vertical speed setpoint was set to 0.5m/s descent rate, but upon
guidance_v_mode_changed it was set back to zero so FAILSAFE was essentially alitude hold.
Merge branch 'master' into ardrone_to_master
[gps_sirf] minor fix