Update to SFML Tiled map loader

Just a short post to say that I finally got round to updating the rendering part of my Tiled map loader for SFML. Originally tile maps were rendered by creating a single sprite for every single tile, but this introduced a severe and occasionally unacceptable performance hit. Now that I've finished messing around with the QuadTree part I've had time to turn my attention to using a vertex array to render the tiles. You can read about why vertex arrays are so much more efficient here, to save me explaining just why you can get, in some cases, an improvement in performance of up to 1000fps on reasonable hardware. The updated files are available to download from the original post. I've not had time to thoroughly test the update across all platforms, however, so please let me know of any bugs.