Restoring computation output after disconnect in Notebook

Following this discussion https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/jupyter/8hyGKoBY6O0/RyEDDyOZAQAJ, I'd like to open an issue to track down progress on this feature.

The idea would be to add the capability to restore output of a running kernel after client reconnection.

Feel free to ask me to move this issue in a more appropriate jupyter project if needed.

Start with the linked Google Groups discussion and trace how the notebook client reconnects to a running kernel and receives computation output. No repository file, test, or entry point is named; done means defining and implementing restoration of that output after reconnection and verifying the behavior.

Written by the indexing model from the issue text.