Add pixel effects (love-glsl)

src/modules/graphics/opengl/Graphics.h

@@ -42,6 +42,7 @@
 #include "SpriteBatch.h"
 #include "ParticleSystem.h"
 #include "Framebuffer.h"
+#include "PixelEffect.h"
 
 namespace love
 {
@@ -288,6 +289,8 @@ namespace opengl
 
 		Framebuffer * newFramebuffer(int width, int height);
 
+		PixelEffect * newPixelEffect(const std::string& code);
+
 		/**
 		* Sets the foreground color.
 		* @param c The new foreground color.