Freezes the dev toolchain (numpy, pandas, pillow, mpyq, odfpy, asarPy,
defusedxml, python-dateutil, six) so any machine rebuilds .venv from this
instead of copying the 176MB virtualenv. Supports the multi-machine workflow:
clone via git, then 'python -m venv .venv && .venv/bin/pip install -r requirements.txt'.
DuvelCorp