[conf] udev rules: add dfu devices to plugdev group
[ahrs] remove old ekf/lkf algos
[conf] error instead of warning on stabilization euler
[sim] add launch and noground options to pprzsim-launch
[paparazzi center] improve backup message
[pprz_center] Added Get Help dialogue to Help menu
rename and fix conf/flight_plans/CMAC.xml
Merge remote-tracking branch 'upstream/master'
switch radio_control subsystem to ppm because spektrum seems to be broken
clean up airframes/examples/bixler_px4fmu.xml, add comments