#32 Depth sort DSC Nebula Mesh objects

[Selden Ball]

DSC Nebula Mesh objects are not depth sorted. Instead, they and their component meshes are drawn in the order that they are read by Celestia.

It would help a lot if they were properly depth sorted.

I think that depth sorting within a Nebula Mesh should have higher priority than depth sorting among different Meshes. An Addon designer can easily specify the order that separate Nebulae are drawn, but cannot control the order of the meshes within a model.