Change description/title, libGdx API changes and more.

This pr among other improvements 
* Fixes libGDX API changes libgdx/libgdx@d35eb11ba71a4e571c6cd36723cf326cca059ae3, more info in the [blog](http://www.badlogicgames.com/wordpress/?p=3322).
* Adds the possibility to change the title and description of Scenes/Elements (the latter not tested yet because there si no Note for SceneElements).
* Fixes other minor bugs.