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.
Solaris' CC. Fixed a bug in fg_debug.c with how the fgPrintf() wrapper
passed arguments along to the real printf(). Also incorporated HUD changes
by Michele America.
