Add "develop" dependencies for the presenter

- the Jupyter notebooks are assumed to be run within an installation of
  the Anaconda Distribution (version 2019-07 with Python 3.7.3) by the
  students (assumed to be total beginners)
- for the presenter some special third-party libraries are added to
  allow for executable code cells in presentation mode (via rise)
- black / blackcellmagic provide a convenient way to style the code
  while working on the notebooks