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/acidtrip.glsl

@@ -1,11 +1,4 @@
-SAMPLER_BINDING(9) uniform sampler2D samp9;
-
-out vec4 ocol0;
-in vec2 uv0;
-
-uniform vec4 resolution;
-
 void main()
 {
-	ocol0 = (texture(samp9, uv0+resolution.zw) - texture(samp9, uv0-resolution.zw)) * 8.0;
+	SetOutput((SampleOffset(int2(1, 1)) - SampleOffset(int2(-1, -1))) * 8.0);
 }