Windows8 DirectX 11 compatibility

[bagobor]

According MSDN D3DX11FilterTexture is obsolete and we must use DirectXTex library, GenerateMipMaps and GenerateMipMaps3D.

http://msdn.microsoft.com/en-us/library/windows/desktop/ff476290(v=vs.85).aspx http://directxtex.codeplex.com/