This might be useful for diffing against when your doc suddenly
doesn't build and you don't know why.  This doesn't save all the files
that go into making the doc.  It would be interesting to try to
snapshot them in some way.  It might even be interesting to collect
all the various files from all over and stik them in a dir so that
every build also makes a minimal one-dir version for slinging around.
Alas, this does none of that.

 * Make -rXXXX versions for all builds, not just drafts
 * Add draft plugin
 * In template, set draft to trigger on both True and 'True'
 * Move path into PIPELINE definition
 * Silence some echo
 * Use .tex instead of intermediate_ltx
 * Simplify some bash
 * Let the plugin handle draft instead of passing it as an option
 * Cleanup .tex files

We can now do redacted and draft at the same time.

Refactor the jinja rendering and the redaction as a pipeline of
filters that run as needed.

It works, but needs some cleanup and documentation

When a venv is created, 'click' will now be installed into it.

This also removes the "dd" that was accidentally introduced into the
variable's value in commit 8463ab1fd21e, the same commit that made the
variable unused (I think we can guess the vi-ism that happened here).
So if we're ever restoring this variable, remember to remove the typo.

Those are backup files or autosave files, and they muck up the build
process, especially if they're a link to a file that doesn't exist.

Don't print all the possible 'make foo.pdf' commands when there are so
many source files (not all of which are necessarily even buildable on
their own) that the list would be very long.

Move the LaTeX template files and the get_revision script from OTS's
private SVN tree to here.  Rewrite README.md.  Clean up the Makefile,
moving all documentation into README.md removing the "VIEW=true"
feature as discussed with James.

Use spaces instead of TABs for the left-side whitespace on line inside
the shell expression.  Break the first line into two lines, and on all
lines move the continuation backslashes leftward to stay within 80 cols.