RSSFeedVisited is now the more appropriately abstract UrlVisisted ST.
Untested fix for "DTD is prohibited" XmlReader exception.
RSSFeedVisited is now UrlVisited
Additional try-catch blocks with exception being emitted as a signal.
Fix issue when the joining table's FK references the actual table (and thus the ID field) rather than another table with the same reference, where we join on FK's on both sides of the =.