Implement mechanisms for extra signalling in the Binlog...

 - New optional conflict flags, transported by v2 Binlog events in
   the Binlog extra info area.
 - Two values currently : Refresh_op and Reflect_op
 - New reserved AnyValue codes, transferred through a cluster from
   NdbApi -> NdbApi event Api.
 - Test to show that the Binlog flag setting works

The new signalling is not yet used.