PX4: added support for the MPU6000 on the v2.4 Pixhawk
PX4: start all sensor types on PX4

this allows for secondary sensors
build: reduced PX4 warnings and avoid rebuilding when possible
PX4: added -Wno-packed

we know that packed data structures are not as efficient
build: fixed a build cmp warning
PX4: change FMUv2 bootloader USB ID to 0x0011
PX4: added automatic IO firmware update