Direct3D 9 Bug Fixes

Figured out what was causing the texture binding problems with models, I
partly had GetPrimCount on primitives wrong, the function should return
the number of triangles on the primitive for DX. I also was creating an
index buffer on models which did not need them, and was not enabling the
correct blend mode in screen_init. The only problem left is having DX's
sprite batching class running at the same time you draw a model or make a
call to SetFVF, it will make it so there is no backface culling on
objects, will investigate more. Please merge when ready.