New P-51D aircraft model from Hal Engel

I've replaced the older P-51D flight model in JSBSim CVS with the extensively researched and meticulously crafted version by Hal Engel. This model has been discussed at length in the FlightGear forums. You can find that forum discussion here: http://www.flightgear.org/forums/viewtopic.php?f=4&t=7494&p=71999&hilit=jsbsim#p71999. The files placed into JSBSim CVS only represent the flight model (Engines, Systems, etc.), but the tar file mentioned in the forum includes the 3D model, flight manuals, etc.