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

--HG--
branch : dynamiccore2

src/modules/image/CompressedImageData.cpp

@@ -25,6 +25,8 @@ namespace love
 namespace image
 {
 
+love::Type CompressedImageData::type(&Data::type);
+
 CompressedImageData::CompressedImageData()
 	: format(FORMAT_UNKNOWN)
 	, sRGB(false)