Fixed the autopilot integration so it should be able to update it's control
positions every time the internal flight model loop is run, and not just
once per rendered frame.
Added a routine to do the necessary stuff to force an arbitrary altitude
change.
Gave the Navion engine just a tad more power.
can use this to enforce a "hard" ground. We still need to enforce some
bounds checking so that we don't try to lookup data points outside the
grid data set.
