+- New config option: allow_duplicate_users which determines whether
+ or not to kill older sessions with the same username.
+- Show session open time in "show session"/"show user" detailed output.
+- Have slaves with BGP configured drop BGP on receipt of a shutdown
+ signal, but hang about for an additional 5s to process any remaining
+ traffic.
+- Run regular_cleanups after processing the results of the select,
+ looking at a sufficient slice of each table to ensure that all
+ entries are examined at least once per second.