Open source benefits - game is noticeably faster!

Thanks to github user bigfootbrz, who completely rewrote the wall renderer, the game now spends 8-15ms less time per frame on, err, rendering the walls. That's about one more fps, which for a game running 5-10 fps, is huge!

It also has the benefit of freeing up nearly 5k of memory... for music?

Thank you so much, bigfootbrz!