Remove confusing comment in AUTHORS list

The comment section of the authors list mentioned two lines that had
already been removed.  This commit removes those comments.
Make minor changes to wording of preambles

This commit makes references to the author list and license more
specific (it actually gives the appendix).
Make URLs in the FDL live
Flatten directory structure

This commit moves the subdirectories of the `tex` directory into the top
level directory.