DrumKit V0.02 -> DK421 V0.02

I've been working on my DrumKit again, since I don't get to play with my Nokia 770. I came up with a better name for this revision, DK421. It doesn't mean anything. Well, it kinda does. It came from a Stormtrooper in ANH ("TK421, Why aren't you at your post? TK421, respond.")

There isn't a lot of change in this version. I re-read the API for javax.sound.sampled and re-wrote the SoundClip class (formerly KitClip) from scratch. It think it's cleaner and more usefull for other projects now.

I also added in a file chooser class, DrumChooser so there aren't any absolute paths in the source anymore. I also added to that class a minor key-fetching function. I hope to make the kit's expandable, as many drums as you can until you hit a LineUnavailableException.

The GUI hasn't changed a lick, and I need to clean it up and develop a new layout for it and for the "multiple-drum" expandable version. It's surprising what you can learn from an API.