Shader::SetUniform override, and implement most of the FBO code for
the Direct3D backend.

issues that were introduced with the Direct3D changes.

retrieve the constant's register index in the description table. This also
allows us to use a single uniform handle for both the vertex and pixel
shaders in a PS3 Cg program.

"shader" source directory since we have "gpu".

for both OpenGL and the PS3.

will let us cache shaders.