[WINED3D 2/9] Add the bulk of the GLSL string generation functions

[H. Verbeet]

Is making the distinction between rgba and xyzw really needed? xyzw /
rgba / stpq should be equivalent and the distinction is mostly for
readability if you know the variable type. However, since you can't
decided that purely based on whether something is a vertex shader or a
pixel shader, the way it's currently done might be misleading in some
cases.