* Use GL vertex buffers and index buffers for 3D model rendering
* Use material or average vertex color for bounding boxes instead of red
* Reinstate bounding box rendering with GL vertex/index buffers
* Use compact vertex/index data representation
- 8-bit normals
- 8-bit colors
- 16-bit or 32-bit indices, depending on model size
This should improve performance a bit on lower end GPUs with less memory
and bandwidth.
Fixes#4112