mpu6k: set hardware filter during ACCELIOCLOWPASS

also set from GYROIOCLOWPASS

Conflicts:
	mavlink/include/mavlink/v1.0
Set filter frequency for hardware and software in parallel, always do so in the same order
Merge remote-tracking branch 'upstream' into master_obcfailsafe
remove wrong comments
enable engine failure circuit breaker
add and activate circuit breaker for gps failure detection