add libretro shaders or colorization support

[eadmaster]

I'd like to use my libretro shader for colorization with VBB.

[SupernaviX]

Hi!

That colorization looks pretty good, but I think that supporting arbitrary shaders the way libretro does would be hard to implement and hard for casual users to set up.

How would you feel about me adding a "shaders" option and bundling your shader in the app instead?

[eadmaster]

sure, no problem.... i still think would be nice having custom shaders to easily experiment with per-game palettes and other effects.

[SupernaviX]

That would be nice, but libretro shaders look complicated. They support arbitrary parameters based on #pragma statements, let you use textures from files, expect the environment to meet some contract... I learned just enough glsl to make a "color this greyscale image" effect, I don't think I'm up to building all that right now

[jakedowns]

I'd like to use my libretro shader for colorization with VBB.

i really like this palette. i might look into a way to load this if i get the time :D