Webkit2 support

[sdumetz]

Would it be possible to port topcube as to work with webkit2 (libwebkit2gtk-3-0-dev on debian)

As I understand, webgl support has been greatly improved in this version and it's a feature I'd greatly appreciate for my own use.

I've begun working on the subject, but don't know well differences btween webkit and webkit2. Could someone familiar with the matter tell me if there is much trouble to expect in this regard?