Fixes a bunch of graphic glitches in WildStar on Nvidia.

They should be generally supported by the existing code.
Specific missing format conversions are caught and reported by
D3DXLoadSurfaceFromMemory(), which is called directly or indirectly
from here.

Include pathnames are passed unchanged to ID3DInclude objects so e.g.
if a file is included as "path/file.h" the full pathname will have
mixed slashes.