Tweak URL formatting

- Adds a quote-style '<' and '>' to urls.
Clean up package loading in preamble

Basically, just list them in alphabetical order.
Change chapter and sectioning

This commit removes the "parts" and replaces them with chapters;
it also bumps every   section type down to reflect the change.
The sections now do not reset at new parts.

As part of this change, I've removed the "AUTHORS.tex" file and
just put myself as the author.
Tweak URL formatting

Replace "<address>" with "<<address>>" (but prettier) and remove
some trailing "/"es.
Merge branch 'master' into rewrite-prob

Conflicts:
	LICENSE.tex
	analysis/exercises.tex
	analysis/introduction.tex
	core_econometrics.tex
	probability/bayesian.tex
	probability/exercises.tex
	regression/asymptotics.tex
	regression/estimation.tex
	regression/inference.tex
	regression/properties.tex
	statistics/estimators.tex
	statistics/hypothesis_testing.tex
	statistics/intervals.tex
	statistics/introduction.tex
	statistics/optimality.tex
	tex/preamble.tex
Bugfix: code listings and figure display

Adds an 'end' marker to stop code listings from displaying the
entire file. Also moves the model-selection graphs to the right
part of the file.
Version 0.7.2 released

* Bugfix: successfully remove ligatures from monospaced text
* Convert most of the R code to Julia. (Everything except what's in
  the Bayesian material so far.)
* Decrease margins and increase font to reduce page count while
  keeping the text readable.
* Reorganize the material within each part and change the formatting
  from "parts" to "chapters" to decrease pagecount.
* Remove the AUTHORS.tex file (until there's another author).
* Moves the FDL to the end of the book (after the bibliography) to
  make it easier to avoid printing.
Merge branch 'master' into rewrite-prob