JupyterLab interface

[pauleve]

We should consider offering the jupyterlab interface as part of the docker, probably as the default at some point.

However, jupyterlab disallows injecting javascript, which breaks the insertion of menus and other tricks to improve the interactivity (file upload, etc.). I've also seen related issues with matplotlib.

Thus, we should ever consider moving some code to proper extensions, or find a way to enable javascript injection in notebooks.

In the meantime, we can still include jupyterlab and give a --lab option to the command line to use it, if there is some demand for it.