List contributors in AUTHORS.tex

I've moved a list of the contributors (just me, at this point) into the
separate AUTHORS.tex file and provided a wrapper file to generate it as
a standalone pdf.  This change also required rewriting all of the
copyright notices throughout the source code.
Move 'shared' files into local directories

Maintaining a separate shared preamble and bibtex file seems pretty
unnecessary right now, since things are in so much flux.  So this commit
moves those files into the main 'tex' directory and also dumps the
relevant files from the tufte-latex project into the directory as well
(their repo's a bit bloated with pdfs, etc).