Show "updated by at" on replies and threads #675
Description
Show when and by who a reply or thread was last updated. We don't need a full edit log, just an indication that a post was edited by a specific person at a specific time. This is useful to see who made an update and if a reply or thread has received changes.
There's a good first try here but it was a bit too extensive: #723
More implementation info here: #723 (comment)