use 9x15 font from SDL_gfx

I think the SDL_gfx fonts look better than the current one, which a couple of people I've demoed load81 to have complained about.

If you like a different SDL_gfx font better I can embed it instead: http://www.randomlynx.net/temp/SDL_gfx-Fonts.jpg

[Before](http://i.imgur.com/eVFXU.png)
[After](http://i.imgur.com/Bm79W.png)