Build type information on first use (load-time), instead of using a hardcoded list

--HG--
branch : dynamiccore2

src/modules/graphics/opengl/SpriteBatch.cpp

@@ -41,6 +41,8 @@ namespace graphics
 namespace opengl
 {
 
+love::Type SpriteBatch::type(&Drawable::type);
+
 SpriteBatch::SpriteBatch(Texture *texture, int size, Mesh::Usage usage)
 	: texture(texture)
 	, size(size)