Fix breakage caused by transaction changes. Sorry for the huge checkin message - I was only intending to implement [SF#496356] but I found a number of places where things had been broken by transactions: . modified ROUNDUPDBSENDMAILDEBUG to be SENDMAILDEBUG and hold a filename for _all_ roundup-generated smtp messages to be sent to. . the transaction cache had broken the roundupdb.Class set() reactors . newly-created author users in the mailgw weren't being committed to the db Stuff that made it into CHANGES.txt (ie. the stuff I was actually working on when I found that stuff :): . [SF#496356] Use threading in messages . detectors were being registered multiple times . added tests for mailgw . much better attaching of erroneous messages in the mail gateway