Finish text and remove draft watermark

Write the conclusion; make a few tweaks to the Executive Summary; add
a CC-BY-SA copyright notice; make various minor wording changes
throughout the document; change all ``uneven" quotation marks to
``even'' quotation marks (apparently both are valid LaTeX, but... I
mean... do I even have to explain why the first bothers me?  Was I
raised by wolves?  No.  No, I was not.  Furthermore, Emacs' syntax
colorization handles the second but not the first); put an
introductory paragraph before the BUSL table; in the BUSL table, add
question marks next to some dates about which we are uncertain.