Removed warnings when compiling CSFML in release mode

Changed samples images
Added an effect to the post-fx sample

git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/branches/sfml2@1008 4e206d99-4929-0410-ac5d-dfc041789085

dotnet/samples/bin/datas/post-fx/pixelate.sfx

@@ -0,0 +1,11 @@
+texture framebuffer
+vec2 mouse
+
+effect
+{
+	float factor = 5 + 100 * length(mouse);
+
+	vec2 pos = floor(_in * factor) / factor;
+
+	_out = framebuffer(pos);	
+}