[ODE] Merging multiple geoms into a single trimesh - a few issues

[Geoff Carlton]

Ok, good to see we're all on the same wavelength. :-)

We're probably all going to tailor a solution for our own needs.  
However, if it came to a "common" solution merged into ode, I think 
storing 2 triangle indexes is a more general way to go.

For example, I have materials, but they are grouped, so I can obtain the 
material index in a manner such as this:
    material 0: index 0 -> 30
    material 1: index 31->100
This is a different way than a set of stored material ids per triangle, 
and it would be inefficient to make a huge list of ids that were 
practically identical.

Also, it may be useful to be able to get our hands on the actual 
triangle, for particle systems, breaking glass, etc.

Geoff