Change all the post processing shaders to the new system.

Removes the README.txt file in favour of a new wiki page I'm going to generate.

Data/Sys/Shaders/sepia.glsl

@@ -1,11 +1,6 @@
-SAMPLER_BINDING(9) uniform sampler2D samp9;
-
-out vec4 ocol0;
-in vec2 uv0;
-
 void main()
 {
-	vec4 c0 = texture(samp9, uv0);
+	float4 c0 = Sample();
 
 	// Same coefficients as grayscale2 at this point
 	float avg = (0.222 * c0.r) + (0.707 * c0.g) + (0.071 * c0.b);
@@ -14,5 +9,5 @@ void main()
 	// Not sure about these coefficients, they just seem to produce the proper yellow
 	float green=avg*.75;
 	float blue=avg*.5;
-	ocol0 = vec4(red, green, blue, c0.a);
+	SetOutput(float4(red, green, blue, c0.a));
 }