After refurbishing the project we prepare a new relaease.
There are no changes with respect to the contents as compared to v0.0.0
that are noteworthy release notes.

Reason: RISE only works in the older Jupyter Notebook app
and not in the more commonly used JupyterLab app

Add a short title/description into the filename of a notebook
holding exercises. In the past, students often did not find
the exercise files right away in class.

- add a session "doctests" to nox
- run it as a pre-commit hook

- add a couple of doctests
- fix failing existing doctests

- upgrade jupyterlab
- upgrade RISE
- upgrade transient dependencies:
  + nest-asyncio
  + notebook
  + pandocfilters
  + pygments
  + virtualenv
- pin transient dependencies:
  + flake8
  + socks
  + webpdf

- add sample_package:
  + __init__.py => high-level description and imports
  + matrix.py => define a Matrix class
  + vector.py => define a Vector class
  + utils.py => package-wide utilities
- streamline the code snippets in the chapter 11 notebooks
  to align with the sample_package