custom shaders support

[eadmaster]

shaders are becoming a popular way to enhance the graphics, and currently the only way to use them is the "Mudlord's shader injector that only works on an old Rice plugin on PJ64" http://code.google.com/p/mupen64plus/issues/detail?id=517

[death-droid]

A new shader support is in the works, actually in contact with mudlord with the best way to actually add full screen shader support since I have little to no idea. From what I've gathered, once weve finished finshed drawing a scene we neeed to convert it to a quad and then apply the shader to that.