Added property-controlled pylons to the A-4, for external stores modelling.
The harrier now has working auto-stabilization, making it *vastly* easier
to control in hover and slow flight.
I just checked in YASim changes that allow for more cleaner export of
control output to the property tree (and flaps now extend slowly now,
to boot). But this breaks the XML syntax in an incompatible way, so
you'll need to update your planes in order to run the code in CVS.
