made Framebuffer Volatile and fixed a few bugs

src/modules/graphics/opengl/Framebuffer.h

@@ -2,6 +2,7 @@
 #define LOVE_GRAPHICS_FRAMEBUFFER_H
 
 #include <graphics/Drawable.h>
+#include <graphics/Volatile.h>
 #include <image/Image.h>
 #include <image/ImageData.h>
 #include <common/math.h>
@@ -15,7 +16,7 @@ namespace graphics
 namespace opengl
 {
 
-	class Framebuffer : public Drawable
+	class Framebuffer : public Drawable, public Volatile
 	{
 	public:
 		Framebuffer(int width, int height);
@@ -31,6 +32,9 @@ namespace opengl
 
 		virtual void draw(float x, float y, float angle, float sx, float sy, float ox, float oy) const;
 		love::image::ImageData * getImageData(love::image::Image * image);
+		
+		bool loadVolatile();
+		void unloadVolatile();
 
 	private:
 		GLsizei width;