Experiment with shader parameters.
Parse params from cgp.
Set parameter uniforms.
Expose currently selected shader via poke interface.
Support aliased pass names from CGP/GLSLP.
Set up shader defines for aliases.
Don't make Cg argv static.
Can tweak shader parameters from RGUI.

Just need to figure out how to handle parameter saving now.
Can save parameters. Can tweak on RGUI presets and current shader.
Rebase fix.
Merge pull request #706 from libretro/shader-parameter

Shader parameter