Add submodules for external libraries

Adds submodules for external libraries used in the paper and changes the source
code to use these local copies instead of installed versions.
Pull code out of noweb

Breaks up the monolithic noweb file, Documentation.nw, into many smaller source
code files, mostly in R.
Remove zip-archive target from Makefile

Archiving as a zip file will have to be done by hand now
Update ignore list
Clean up build process

Shortens file names and simplifies build path for the paper and monte carlo.  Also sets a
few parameters to govern empirics and monte carlo (this was done through the noweb
document before).
Minor change to 'thanks' section
Fix typo in formula for asymptotic variance

Changes the formula for g_t so that the summation uses s, not t, as an index.
Tweak formula of asymptotic variance

Changes the formula of the asymptotic variance of the oos statistic to
use the fact that x_s (y_{s+1} - x_s'\beta) is an MDS.
Minor code reorganization in submodule

Splits the mixed-window functions into a separate R file from the DMW
functions in the oosanalysis R library.
Ongoing tweaks to main text
Remove unsubstantiated power claim from conclusion.
Remove citation to technical appendix

Since I'm not using literate programming for the technical appendices any
more, I've decided not to cite them separately either.
Minor changes to the wording
Removed paper from bibtex
Changed paper margins to more standard 1.25in
Remove custom section-header style

This commit changes the styling of the section labels back to the default style.
Add another latex surplus file type to ignore list.
Minor changes to wording in theorems 1 and 3

Changes the phrasing slightly, but should not change the content or meaning
of any statements in the paper.
Remove weak-stationarity requirement in theorem 1

Under the null, the mean is zero; so assuming covariance stationarity is
just a restriction on the variances.  That restriction isn't necessary for
the CLT to hold, so I'm removing it.
Add requirement of constant mean to theorem 3

Without a constant mean, the OOS bootstrap used in Theorem 3 is not valid.
So I'm adding the assumption.