Changes to the Cyrus IMAP Server since 2.5.7

Murder changes

      * Allow replicated backends in a discrete Murder to both actively
        participate in the Murder. 
      * When choosing between ANNOTATEMORE and METADATA, favour what the
        client used. 

Other changes

      * cyr_dbtool now supports improved_mboxlist_sort (-M) 

Bug fixes

      * Fixed: master on pselect systems no longer chokes on repeated
        interrupts (thanks Jens Erat and team) 
