Remove incomplete lists of authors entirely.

The lists of authors in each part has been continually out of date and
incomplete. There are multiple examples, here are a few:

* In September 2005, John Sullivan made improvements and was not placed on
the Authors lists until I did so in a March 2014 commit.

* In March 2014, Martin Michlmayr submitted many patches, but was not
placed on the Authors lists until I did so in an April 2014 commit.

There is no easy way to keep these Authors lists current, and they aren't
necessary under CC-BY-SA-4.0 anyway, so I herein remove the Authors lists.
Additionally, previous commit added "published sources" in each part, which
is more static and easier to keep up to date and provides similar
information.