this will reduce confusion when searching for FLIGHT_LAND_* and you get a bunch of takeoff related hits. It will also make more sense when the landing library fully manages the FLIGHT_LAND stage entirely because it will not mange FLIGHT_LAND_ABORT

Using a global .dir-locals.el file is a better alternative than
reincluding the same emacs header in every file of the project.

now that we have separated RC input from servo output with
SERVO_RNG_ENABLE=1 we can do full automatic servo trimming as an
option

this is needed to ensure that changes in RCn_MIN/MAX don't cause
changes in the output handling for elevon nd vtail planes

this provides a framework for other output mixing types

this can be achieved with THR_MAX parameter instead

this makes it possible to setup an elevon plane without changing the
transmitter reversals

Revert "ArduPlane: Convert references to AP_Airspeed.  Added automatic migration of ARSPD_FBW_MIN and ARSPD_FBW_MAX (plane parameter) to ARSPD_FBW_MIN and ARSPD_FBW_MAX (library parameter)."

This reverts commit da1b18d9.

ArduPlane: Convert references to AP_Airspeed.  Added automatic migration of ARSPD_FBW_MIN and ARSPD_FBW_MAX (plane parameter) to ARSPD_FBW_MIN and ARSPD_FBW_MAX (library parameter).

this allows for automatic engine start and restart

this fixes a problem where modes like loiter and auto would allow for
rudder stick mixing even with STICK_MIXING=0

this really didn't help much and slows down startup

Fixed differential spoilers support, added elevon offset
See PR #2935