Mavenize the project

[ramiromagalhaes]

This is a request to rearrange the project so that it can be built with Maven, maybe separating it in modules.

[apjanke]

I think I could do this. Is there interest from the maintainers in my submitting a PR?

[apjanke]

This turns out to be pretty straightforward. Here's an example of how you could do it: https://github.com/apjanke/Prefuse/commit/e84b51ef99752801d62918ddf10fe5120271f140.