Add tufte-latex mirror as subdirectory

Add the EconometricsLibrary's mirror of the tufte-latex project as a subdirectory.
Add latex-shared repo as subtree

Add shared repo and update its ignore list.
Move LaTeX preamble to common file in shared repo

Most of the commands in the preamble are common to all of the LaTeX
documents produced by this project.  Right now it just has a few
workarounds and package loadings, but I expect to put a library of
macros in the common preamble soon.
Group documents into several books

Moves all of the individual LaTeX documents into four separate 'books' and adds
licensing information to each one.
Add notes about subtrees to project README
Update shared LaTeX files
Update appearance

* Fix table of contents so that chapter headings appear (they've been made into 'parts')
* Update author to be more informative
* Set up local LaTeX preamble
* Eliminate extra blank pages by switching to tufte-handout
Refactor Makefile slightly

Add the subdirectory for each document automatically.
Bump version to 0.1.0

This release gets the text decently organized and presented.  This
groups the sections of the textbook into four largish handouts that
use the tufte-latex handout style, and moves a lot of the preamble
material to files that are shared across several other projects.
Merge branch 'dev', version 0.1.0

This release gets the text decently organized and presented.  This
groups the sections of the textbook into four largish handouts that
use the tufte-latex handout style, and moves a lot of the preamble
material to files that are shared across several other projects.