v2.2.16 release candidate released

[Timo Sirainen]

http://dovecot.org/releases/2.2/rc/dovecot-2.2.16.rc1.tar.gz
http://dovecot.org/releases/2.2/rc/dovecot-2.2.16.rc1.tar.gz.sig

Looks like it's been a long time since v2.2.15. There have been a ton of changes since it was released though, so here's a release candidate first to find out if somebody can find any bugs before the final v2.2.16.

Unfortunately I haven't had time/energy to read Dovecot mailing list for a while now. I'm hoping this will change, but I don't really expect it to happen anytime soon. On the positive side for Dovecot, it's now becoming used in more and more multi-million user installations, which brings all kinds of nice new improvements.

The largest changes since v2.2.15:

	* dbox: Resyncing (e.g. doveadm force-resync) no longer deletes
	  dovecot.index.cache file. The cache file was rarely the problem
	  so this just caused unnecessary slowness.
	* Mailbox name limits changed during mailbox creation: Each part of
	  a hierarchical name (e.g. "x" or "y" in "x/y") can now be up to 255
	  chars long (instead of 200). This also reduces the max number of
	  hierarchical levels to 16 (instead of 20) to keep the maximum name
	  length 4096 (a common PATH_MAX limit). The 255 char limit is
	  hopefully large enough for migrations from all existing systems.
	  It's also the limit on many filesystems.

	+ director: Added director_consistent_hashing setting to enable
	  consistent hashing (instead of the mostly-random MD5 hashing).
	  This causes fewer user moves between backends when backend counts
	  are changed, which may improve performance (mainly due to caching).
	+ director: Added support for "tags", which allows one director ring
	  to serve multiple backend clusters with different sets of users.
	+ LMTP server: Added lmtp_user_concurrency_limit setting to limit how
	  many LMTP deliveries can be done concurrently for a single user.
	+ LMTP server: Added support for STARTTLS command.
	+ If logging data is generated faster than it can be written, log a
	  warning about it and show information about it in log process's
	  process title in ps output. Also don't allow a single service to
	  flood too long at the cost of delaying other services' logging.
	+ stats: Added support for getting global statistics.
	+ stats: Use the same session IDs as the rest of Dovecot.
	+ stats: Plugins can now create their own statistics fields
	+ doveadm server: Non-mail related commands can now also be used
	  via doveadm server (TCP socket).
	+ doveadm proxying: passdb lookup can now override doveadm_port and
	  change the username.
	+ doveadm: Search query supports now "oldestonly" parameter to stop
	  immediately on the first non-match. This can be used to optimize:
	  doveadm expunge mailbox Trash savedbefore 30d oldestonly
	+ doveadm: Added "save" command to directly save mails to specified
	  mailbox (bypassing Sieve).
	+ doveadm fetch: Added body.snippet field, which returns the first
	  100 chars of a message without whitespace or HTML tags. The result
	  is stored into dovecot.index.cache, so it can be fetched efficiently.
	+ dsync: Added -t <timestamp> parameter to sync only mails newer than
	  the given received-timestamp.
	+ dsync: Added -F [-]<flag> parameter to sync only mails with[out] the
	  given flag/keyword.
	+ dsync: Added -a <mailbox> parameter to specify the virtual mailbox
	  containing user's all mails. If this mailbox is already found to
	  contain the wanted mail (by its GUID), the message is copied from
	  there instead of being re-saved. (This isn't efficient enough yet
	  for incremental replication.)
	+ dsync: -m parameter can now specify \Special-use names for mailboxes.
	+ imapc: Added imapc_features=gmail-migration to help migrations from
	  GMail. See http://wiki2.dovecot.org/Migration/Gmail
	+ imapc: Added imapc_features=search to support IMAP SEARCH command.
	  (Currently requires ESEARCH support from remote server.)
	+ expire plugin: Added expire_cache=yes setting to cache most of the
	  database lookups in dovecot index files.
	+ quota: If overquota-flag in userdb doesn't match the current quota
	  usage, execute a configured script.
	+ redis dict: Added support for expiring keys (:expire_secs=n) and
	  specifying the database number (:db=n)
	- auth: Don't crash if master user login is attempted without
	  any configured master=yes passdbs
	- Parsing UTF-8 text for mails could have caused broken results
	  sometimes if buffering was split in the middle of a UTF-8 character.
	  This affected at least searching messages.
	- String sanitization for some logged output wasn't done properly:
	  UTF-8 text could have been truncated wrongly or the truncation may
	  not have happened at all.
	- fts-lucene: Lookups from virtual mailbox consisting of over 32
	  physical mailboxes could have caused crashes.