This patch only affects aircraft (AI Models) that have no predefined

This patch only affects aircraft (AI Models) that have no predefined
flightplan.  Such aircraft are given some initial conditions that they
fly with.  They proceed on in "freeflight" mode indefinitely.  For example,
there is a refueling demo where the tanker starts at 3000', 280 kts, and
in a 15 degree bank, and then continues to orbit indefinitely.

For these aircraft with no flightplan, I have added several control nodes in
controls/flight that allow a script or menu or external application to set
heading, altitude, bank angle, and speed.  This permits some level of interactive
or scripted control over AI aircraft.