ess vee gee to three dee

It's super slow (O(n^2) where n is # lines, but it works for single polygons (no nesting right now)

To set up: ./setup.sh

To run: either use pycharm (should detect the virtualenv automatically) or source venv/bin/activate then run stlify.py with a file name (e.g. test_svg/squares_cut.svg)

To test: install pytest (pip install pytest) in the virtualenv and run it (py.test) in the git root. If you initialize virtualenv without the setup script, be sure to add your virtualenv directory to the [norecurse] directories in pytest.ini.