zsync-0.2.2 released

A third release within 7 days. There is very little changed in this release, but since it completes the work started in 0.2.1 to make gzip support work properly (which turned out to be easier than I expected), I thought it worth putting out immediately.

I have also updated the technical paper. The details of the optimisations in zsync-0.2.x are now included, and I have refreshed all the empirical data to reflect the new version. We are comparing very favourably with rsync now, with only rsync's -z option able to really beat zsync — but if I get mod_gzip installed, we shall see if zsync can match that, too.