Remove the vertices/triangles limit per surface

[MikeHart66]

I think there is a limit of around 64.000 vertices/triangles per surface. Would be awesome to remove that limitation.

[kfprimm]

Cool, great suggestion.

Unfortunately, it looks like this is a hard limit of D3D7. IDirect3DDevice7::DrawIndexedPrimitiveVB accepts on a WORD (unsigned short) array which has a limit of 65535. Moreover, it's codified as D3DMAXNUMVERTICES.

That being said, the good news is that OpenGL and D3D9+ allow for larger index types so we can remove the limit on those renderers.

So, this will have to wait until we manage to decouple the rendering code from the engine code.