Sling

I decided to do a quick update on this. It's one of the most popular of the several games I've made in the past week!

- Added art created by Ceojac.
- Made some other appearance changes regarding the sling. It looks more rubbery, I think.
- Added a guide path for early levels.
- New game over message provided by Bakasensei.

* I'm looking for sound effects and maybe background music. If you feel like contributing anything, just let me know by replying here or in the shoutbox.