Version 0.0.15

A bunch of small changes and bug fixes. Documentation improvements.

Note: Dumbness with git caused me to blow away all of my tags. I had a tag for each release, but did not realize pushing the project did not push the tags. A bit of hard drive stupidity, and poof. So, no good history for past releases.

These tag numbers correspond to the version number of the project on pypi. If you do pip install filterpy you will (as of now) get version 0.0.15 - this tag.