v1.0.0

Major changes

• Rework setup.py to use package extras and fetch metadata from __init__.py. (#15)
• Add dev package extra for development (including running docs and tests). (#15)

Minor changes

• Switch to CircleCI. (#15)
• Add CI for Python versions (3.6 - 3.10). (#15)
• Fix Jinja2<3.1 version for RTD (see readthedocs/readthedocs.org/issues/9038). (#15)
• Fix broken ReadTheDocs link — thanks @black-puppydog. (#13)