Releasing clldutils

Clone clld/clldutils and switch to the master branch. Then:

Do platform test via tox (making sure statement coverage is at 100%):

tox -r

Make sure flake8 passes (configuration in setup.cfg):

flake8 src/clldutils

Make sure the docs render:
```
cd docs
make clean html
cd ..
```
Change version to the new version number in
- setup.cfg
- src/clldutils/__init__.py
- docs/conf.py
- CHANGES.md
Commit your change of the version number:

git commit -a -m "release <VERSION>"

Create a release tag:

git tag -a v<VERSION> -m "<VERSION> release"

Release to PyPI:

python setup.py clean --all
rm dist/*
python -m build -n
twine upload dist/*

Push to GitHub:

git push origin
git push --tags origin

Increment the version number and append .dev0 to start the new development cycle:
- src/clldutils/__init__.py
- setup.cfg
- docs/conf.py
Commit/push the version change:

git commit -a -m "bump version for development"
git push origin