Book update

[aanno]

Hallo,

I've bought your book to teach my son a bit of programming. We are working on linux where gosu has no mp3 support. Hence I converted the affected files to ogg.

Pull request also includes some gem updates and eclipse files for the dynamic language extension.

Cheers,

aanno

[spajus]

Hi, thank you for buying the book, I hope you enjoy it. I will have to consider merging this PR though, because code samples would get diverged in the book and in this repo - I need to keep them synchronized, so book update should come together. Thank you for contributing, however, I will look into the issue.

[shawn42]

@spajus maybe you could have a current_book_version tag on the examples going forward to make these sorts of things easier?

[spajus]

@shawn42 good idea, I will do that, so this PR can be merged then. But I have second thoughts about including Eclipse configuration in the repo. I believe that code should be editor / IDE agnostic.

[aanno]

Well, I'm ok with just proposing my changes. It is a bit strange that gosu got mp3 support for Win and Mac but not with Linux. And I'm aware that my change is not as focused as it should be.

However, if somebody encounter the same problem, he probably will find this discussion and could fix it...