ipython/ipython — pull request #3939 by minrk (2013-08-07 19:32:40+00:00)
Title: minor checkpoint cleanup

- remember list of checkpoints browser-side
- cleanup references in MenuBar restore list.
There was a closure issue, where multiple menu items would actually all
restore the same checkpoint.

Issues revealed by @rgbkrk/bookstore, which supports multiple checkpoints.

I'm fine if this doesn't get into 1.0, given timing.