IPYNB: add new jupyter notebook generating target #44
Description
Jupyter Notebooks natively support everything that is important for our lecture notes: text, bullet points, headings, figures, code, maths... They even look better in the preview on GitHub than GitHub Markdown :) ... Source references have to be translated via Pandoc anyway, and with the right tools, the code could even become interactive.
Potential disadvantages: Preview only in the browser or in corresponding tools (VSCode, https://colab.google/, ...). Even the preview in the GitHub app fails (but it also does so with math in GH Markdown).