To build the library, you need the following:
- A reasonably modern LaTeX installation. In particular the `minted'
  package should be present.
- A python 3 installation.
- The Pygments python package.

If you have python 3 installed with the `virtualenv' tool, you do not
need to install Pygments in your system globally. You can instead use
the virtualenv tool to install it as follows:

# Create the virtual environment. You only have to do this once ever.
# The filename below has an entry in .gitignore.
virtualenv ./python-venv

# Activate the virtual environment. You must do this once per shell
# session in which you want to build the notebook.
. ./python-virtualenv/bin/activate

# Install Pygments. You only have to do this once.
pip install -r ./requirements.txt