Target #2

I initially wrote this a while back as a worksheet, but never got as far as I wanted to with the actual game. So with this version I've implemented a few more things, as well as tidying some of the original code up and fixing a couple of bugs I'd noticed.

New features:

- Levels, there's 10 of them and the target gets progressively faster with each one
- A rotating sun (doesn't do anything at the moment but I have got an idea)
- Score and arrows in a clearer font
- Sounds
- Mute / Unmute button so sounds can be turned on or off from within the scenario
- Bonuses when you hit more than one balloon in a row
- Big text to give you updates as to what's going on (for levels, bonuses and game over)
- Highscores added
- Balloons now appear more nicely
- Poison balloons take 100 from score
- Target moves more smoothly
- Arrows can go out and come back into the world
- Yellow balloons just give you five arrows
- Hitting the sun now removes all the balloons in the world at once
- Speed of balloons increases with the level
- Balloons only appear in the lower half of the world
- Text now fades out instead of suddenly disappearing

- Now uses the newer Wanderer class instead of the old one (there was a slight bug keeping track of positions outside of the world that's fixed with the new one.)
- Sun now doesn't give bonuses