Added the GUI buttons for the new way of handling test documents
The new way of handling test documents is in. There are still some
things to be worked out (including an unknown folder by default,
statistics calculation)
Everything should be working as it used to, but with the new
infrastructure (except for having an _Unknown_ folder by default) will
do that next.
Fixed a bug where you couldn't add documents to the _Unknown_ folder via
the add test docs button
Improved messages when attempting to add documents more than once.
Documents will now automatically be filtered out if they have already
been added to test or training sets, and will notify the user of which
author has that document.
Updated the Docs tab instructions