Make the shapy instance forkable

[novellac]

Is your feature request related to a problem? Please describe. No problem. Just a feature I would like!

Describe the solution you'd like I would like a button to fork the shapy instance, so I can sort of version it.

Describe alternatives you've considered The share feature is sort of like forking, but not really, because I want to be able to have a copy of the shapy instance, and keep working from the new point.

Additional context None.