Merge pull request #6 from mcmtroffaes/sphinx-docs

Sphinx docs.

Make sphinx doc skeleton, update some docstrings, start API docs
Merge pull request #5 from mcmtroffaes/fix-non-ascii-input

Raise appropriate error when bib file contains non-ascii characters.
Merge pull request #4 from mcmtroffaes/fix-imports

Fixed imports for new package stucture.