Why do you believe you have to? A simple "start afresh" button discarding all the objects would do. Such a tool is essential for experimentation, studying a new tool.
> This, restore and backup will definitely be implemented in the near future.
I hope so. Just dump/load JSON. Lack of this functionality seems killing a great concept. I doubt many people will spend even a minute outlining if the only way they can backup their work result is a screenshot.