Add badges to readme.

Fix typo.

Reformat all code with black.

Fix quote escaping from the previous commit in gendbf.

Style cleanup.

Add .gitignore.

Add module constants for strings used across the code.

Remove six.

Bump up version to 0.5rc.

Remove declaration of support for Py2.7.

Minor corrections in setup.py

Update license from GPL2 to BSD.

Bump up version, update classifiers.

Make ydbf.dump Python 2+3 compatible.

Update examples to be Python 2+3 compatible.