when a torrent finishes downloading, first rename/move the files (if there's a temp directory or .part suffix), then check to fire the completeness callback, then check to fire the ratio limit callback, then check to fire the done callback.

git-svn-id: svn://svn.transmissionbt.com/Transmission/trunk@14125 f4695dd4-2c0a-0410-b89c-da849a56a58e