OpenGL2: Prioritize loading .png images over all others besides .dds.

code/renderergl2/tr_image.c

@@ -2272,10 +2272,10 @@ typedef struct
 // when there are multiple images of different formats available
 static imageExtToLoaderMap_t imageLoaders[ ] =
 {
+	{ "png",  R_LoadPNG },
 	{ "tga",  R_LoadTGA },
 	{ "jpg",  R_LoadJPG },
 	{ "jpeg", R_LoadJPG },
-	{ "png",  R_LoadPNG },
 	{ "pcx",  R_LoadPCX },
 	{ "bmp",  R_LoadBMP }
 };