Direct3D: implement HLSL pixel shading in the rendering pipeline
The user can choose to apply a builtin shader using a selection list
in the options of the Direct3D vout module. A custom shader function
can also be loaded by specifying the path of the shader file.
Many changes since the latest patch proposal: we are not compiling
"shader techniques" anymore but now shader functions using the "main"
entrypoint. All the shaders previously in pixelShader.fx are now
builtins.