Make Reply autorefresh work on the new boards

[fracture91]

Should work like before, and include the features planned for 2.3.0. Take a look at the XHR that gets new posts after you post a reply. That might be useful, but I'm worried that there may be no way around the way XenForo currently only shows you the 3(?) latest posts rather than all the posts made since you posted. At worst, we'll have to scrape the page we're currently on.