Adding Unit Tests

[Skylion007]

When I first programmed this API, I was still in high school and as such, my coding practices had yet to mature. As recent API breakages have shown, I think its time to prioritize adding a unit testing framework to this code base. APIs like duplex may difficult to test, but maybe we can create an scripted implementation of TargetDataLine.

I am also asking all contributors and watchers. Any preferences on what framework? Now that we use maven, it should make the transition much easier.