Master

This is the start of windows support. For now, I'm very afraid of having to convert some shell/autotools files (I'm not a big fan of them).

Anyway, I'm able to compile, not to run tests yet for some (yet) unknown reasons. If I need to make equivalent shell files for windows, I'll instead replace those shell files with Python so it can be run on every system.

You can see the appveyor CI here: https://ci.appveyor.com/project/GuillaumeGomez/librsvg