Add definition of psi to statement of Lemma 6
Restore old proof derived from de Jong to appendix

For semi-completeness and to satisfy a referee, I'm going to provide
an explicit statement of one of de Jong's proofs. This commit restores
one that I had removed in earlier versions of the paper.
Rewrite proof of Lemma 6

Still in progress, but the notation agrees with the rest of the paper.
Merge branch 'master' into lemma_6

Conflicts:
	Appendix.tex
Clean up basic inequality proofs in appendix
Fix hypothetical block size in appendix proof
Move revised statement of Lemma 6 to main document
Merge branch 'lemma_6'

This branch rewrites several parts of Lemma 6.