When trashing a notebook: also offer to go to parent page (rather than home page)

[Martien]

When you trash a notebook, you are offered to:

1. Go to homepage
2. Restore notebook (default)

My workflow is often like so:

1. Fork notebook which I want to change.
2. Edit until happy.
3. Compare fork.
4. Merge changes with parent when happy.
5. Delete fork. <-- it is here that I also want to have the option to go to its parent.