add support for zmg bbcode tag (img with class=zrl) which will eventually get turned into a zid link when rendered for display. TODO - turn photo items and photos uploaded into posts into zmg, then run all incoming bbcode posts through a filter to see if there's a photo from a known hubloc (with an http(s): src attr - not data:) and if so turn it into a zmg. Then fix the zidify functions to look for class="zrl" and we're done.