#42 GIMPACT trimesh update (V0.8)

[crusherfred]

When using the GIMPACT collider, gim_trimesh_update() is only called by dxTriMesh::computeAABB() - this seems to work well when using ODE's spaces (I'm assuming computeAABB() is called when doing the dCollide()), but dCollide() w/o a space requires dGeomGetAABB() on the geoms to force GIMPACT to rebuild the AABBset. This seems extremely slow.