* Retains ability to read from Analog Pin
* Adds ability to read RSSI from PWM channel value as is done in OpenLRSng, EazyUHF, and various other LRS.
* Handles any type of RSSI that provides RSSI values inverted - i.e. when the low value is the best signal and the high value is the worst signal.
* Has different key names from all existing RSSI parameters to provide for a clean break and easier distinguishing.
* Existing parameters are marked as obsolete
add crash detection, allow disengage via param CRASH_DETECT
improved is_flying behavior
take off, landing and hard-landing improvements
add stillness check to is_flying and log it
minimum airspeed is determined ARSPD_FBW_MIN*0.75
setup the MODESWITCH channel as our OVERRIDE_CHAN, allowing for
instant manual passthru in px4io when OVERRIDE_CHAN goes above 1750
This makes for faster switching, and avoids bugs where a still enabled
FMU channel disables override