v2.2.19 release candidate released

[Timo Sirainen]

http://dovecot.org/releases/2.2/rc/dovecot-2.2.19.rc1.tar.gz
http://dovecot.org/releases/2.2/rc/dovecot-2.2.19.rc1.tar.gz.sig

A lot of changes since v2.2.18, so here's a release candidate first. If no bugs are reported, I'm planning on making the final release sometimes this week. The most interesting new features here are the imap-hibernate process, quota count backend and director/proxy improvements.

 * "doveadm director flush" command has a changed meaning now:
   It safely moves users to their wanted backends, instead of simply
   forgetting the mapping entirely and leaving the existing connections
   untouched. Use -F parameter to get the original unsafe behavior.

 + Added support for imap-hiberanate processes.
 + Optimized tracking mailboxes' vsizes (= sum of all messages' size).
   If mailbox_list_index=yes, it's also stored in there. This makes it
   very efficient to look up vsizes for all mailboxes.
 + Added a quota "count" backend, which uses the mailbox vsizes to get
   the current quota usage. It requires using the new quota_vsizes=yes
   setting, which tracks the messages' "virtual sizes" rather than
   "physical sizes". Their distiction is minor and mostly irrelevant
   nowadays (if mail sizes should be counted with LF or CRLF newlines).
 + "doveadm director up/down" commands added. The monitoring script
   should be using these commands instead of changing the vhost count.
   This allows admin to manually disable a server by changing the vhost 
   count to 0 without the monitoring script changing it back.
 + Added support for HAProxy protocol: http://wiki2.dovecot.org/HAProxy
 + Added push-notification plugin framework, which can be used to
   easily implement push notifications to various backends. Implemented
   "ox" backend for notifying Open-Xchange via HTTP/json.
 + imap_logout_format supports more variables now, e.g. number of
   deleted messages.
 + pop3: Added pop3_delete_type setting (related to pop3_deleted_flag).
 + plugin { fts_enforced=yes } setting now fails body searches unless
   it can be done via the full text search engine.
 + Added %{passdb:*} and %{userdb:*} variables to various places
 + auth: Added ":protected" suffix for passdb and userdb fields. If
   used, the field doesn't overwrite an existing field.
 + IMAP/POP3 proxy: If a backend server dies, avoid client reconnection
   spikes by slowly disconnecting clients over time. This is enabled by
   setting login_proxy_max_disconnect_delay=secs passdb extra field.
 + imap: Added new read-only METADATA entries: /private/specialuse,
   /shared/comment, /shared/admin
 + imap: If client disconnects in the middle of a command, log how long
   the command had been running.
 - mdbox: Rebuilding could have caused message's reference count to
   overflow the 16bit number in some situations, causing problems when
   trying to expunge the duplicates.
 - Various search fixes (fts, solr, tika, lib-charset, indexer)
 - Various virtual plugin fixes
 - Various fixes and optimizations to dsync, imapc and pop3-migration
 - imap: Various RFC compliancy and crash fixes to NOTIFY