Updating the "List of GLSL Inputs" to include inputs from the Cg listing

[ArsThaumaturgis]

This commit should document a variety of shader-inputs that are available in both Cg and GLSL, but that were mentioned only in the documentation for the former.

I have, however, chosen to omit the "mat_", "inv_", "tps_", and "itp_" families of inputs, as they appear to duplicate inputs already documented on the page.

(Plus, I note that they're in a style less in keeping with the majority of the inputs documented here.)

Most of what has been added has been taken directly from the "List of Possible Cg Shader Inputs" page, then converted to GLSL syntax and adjusted to fit the style of this page.