Remove unnecessary graphics package
Make the arrows look nicer.

Also make sure the commenting-out of the last lemma really sticks.
(Unfortunate bug in the munger makes this fiddlier than it should be.)
A number of tweaks, including use of <x>'_\bot for stage1 constants.
Work on explaining corrected proof.
Fix capitalisation errors in bib file.
Minor tweaks - starting to think about conclusion
In the interests of space, remove lemma that was an easy induction on \pi