Black & White shaders (classic, SDTV, HDTV)

[aybe]

I’ve added 4 new shaders that produces black & white tones :

download : https://github.com/aybe/RetroArch-shaders

• the poor man’s b&w algorithm

• the algorithm used in SDTV

• the algorithm used in HDTV

• a variation that negates values like the alien vision in AvP

[aybe]

EDIT : screenshots added !