[Dovecot] v2.2 status update

[Timo Sirainen]

So, I'm still planning on getting v2.2.0 out Really Soon now.
Unfortunately I've had to quickly develop some rather large features
still at this stage. I was initially planning on leaving them for v2.3,
but they were a requirement for one project and implementing them now to
v2.2 was the least amount of trouble for me.

(And yes, I'm aware I haven't replied to a lot of emails in this list.
There are about 60 unread ones. Hopefully I'll have time to go through
them this week.)

So, what we have now:

 * dsync can sync ACLs

 * dsync can sync Sieve scripts - Slightly unfinished patch for
Pigeonhole at http://dovecot.org/patches/2.2/doveadm-sieve-plugin.diff

 * dsync does the ACL/Sieve syncing by having implemented generic
mailbox attribute syncing. (The ACLs/Sieve scripts are transparently
mapped into the attribute hierarchy.) ACL plugin also supports now
restricting attribute set/get/iteration. IMAP METADATA extension can be
implemented using mailbox attributes. The dsync/ACL support was the main
reason why I had planned on delaying native IMAP METADATA support until
v2.3, but there's really no reason for that anymore. So expect IMAP
METADATA support also early in v2.2.x (disabled by default). I'll still
need to figure out how to do quota for it.

 * LDAP values can now have DN pointers to other entries that are
queried. (Support for LDAP URLs could probably also be added with little
trouble.) The configuration becomes a bit more complex again, but until
the whole LDAP configuration is redesigned this will work. Example:

user_attrs = \
  =user=%{ldap:uid}, \
  @mail=%{ldap:mailDN}, \
  =uid=%{ldap:uidNumber at mail}, \
  =gid=%{ldap:gidNumber at mail}, \
  =home=%{ldap:rootPath at mail}/%d/%n