David Culp:

David Culp:

1.  Removed aircraft roll on ground.
2.  Decreased descent pitch angle.
3.  Updated flightplans to include <on-ground>
4.  Fixed property indexing, so all AI aircraft have their own property branch

The default value of <on-ground> is false, so you only need to specify it when
on the ground.  For takeoff you need to specify <on-ground>true</on-ground>
for the first waypoint, and for the acceleration waypoint.  For landing you
need to specify it for the touchdown point and any taxi points.

One problem.  WARNING **** There is a bug in the way the property system
works, which causes a segfault, but I don't know if the problem is in the
property code, or in how I'm using it.  After an AI object terminates, if you
access the property tree through the property browser the sim will segfault.