Added support for Windows

While adding support for Windows, I had to change the inclusion paths to be relative to each other, thus `Game/Points.hpp` now includes `../Engine/GFXBean.hpp` and not just `GFXBean.hpp`. So maybe you'll have to adapt your Xcode settings to also use relative paths; afaik it's the more standard way to handle paths.

I've additionally added the Code::Blocks project file, where I link SFML statically. But one of course has to change the include/lib paths to SFML. Feel free to remove it, if you think it's not that useful.

For further points about the code base, take a look at the SFML forum post.