Stronger association between hunk buttons & content

Collating the feedback on 1.9 regarding the positioning of the hunk buttons in the revised diff view.

Several users have been confused because the old diff view had the hunk buttons at the bottom, and now that the diff view has visual containment on files with dividers for hunks, you can misunderstand which hunk (above or below) the buttons relate to.

So one issue is that there should be a stronger visual association between the button and which hunk it affects, and secondly the argument has been made that the buttons should be at the bottom and not the top, because it's only after you read through a hunk that you decide to stage it, so the bottom of the hunk is the most appropriate place, rather than having to scroll back up to find the button.