Create or load triangulation data, pass to navWidget and render

There's a few bugs in the code that prevent it from running in its
current state, most notably the null pointer exception thrown from
the SceneTriangulation's copy constructor. I'm about to introduce
some structural changes to the code, so I thought I'd commit before
changing a lot of stuff.
Don't copy splats or triangulation in NavWidget

NavWidget now uses the actual instance of SplatScene or SceneTrian-
gulation passed in instead of copying it. Because of this, NavWidget
is responsible for the destruction of these objects. Furthermore, I
made the genLoad* methods set the data within NavWidget so that the
calling code doesn't have to. I don't see any other reason why these
methods would be called if not to display the data they're retrieving.

I did encounter an odd message a couple of times when viewing the
triangles. The OpenGL driver stated that the hardware on this system
was insufficient for displaying the data. Oddly, this message did not
appear the last time I tested it, so perhaps there is an issue with
the video memory. I'll have to investigate further if it keeps up.
Update NavWidget when any draw option changes