Patches from Jim Wilson:

Patches from Jim Wilson:

This patch creates a seperate scene graph for the cockpit.  The near plane is
only moved up when in the interior (pilot) view.  This is because with
rounding (I presume) it the visible ground is a bit up higher than it is with
the older nearplane setting.  Not much, but it is enough to bury the wheels.
I suspected this might be true but spliting to two sg's confirms it.  If
necessary we can adjust the model up a bit when in interior view.  This might
be good so we can set the near plane even closer when in the cockpit (its
still at 0.2m).

In general this looks a lot better on my Voodoo with this patch.  No
perceptibel change in frame rate on my system.  In terms of future plans I'd
see the sense in making the model plug into either scene.  This will be
necessary when we have multiple model instances in the frame.