autotest: added AVC_plane location

point along takeoff path
autotest: cope with newer versions of JSBSim
autotest: fixed problem with initial JSBSim headings to east

this avoids an auto-trim problem in JSBSim
autotest: convert Rascal back to a tail dragger
Plane: fixed zero throttle in FBWA glide failsafe
autotest: added -R to sim_vehicle.sh for reverse throttle