Run flake8 in tests
Add flake8-docstrings
Alphabets
PEP8
Simplify `next` and `prev` methods
Restore long url
Merge pull request #20 from incuna/pep8

Add flake8 and flake8-import-order to tests
Update changelog
Bump version to 3.0.0
Merge branch 'master' into coverage

Conflicts:
	Makefile