Log Message:
Update to Dovecot 1.1.12.  Changes since 1.1.11:

* Added :MAILBOXDIR= to mail_location to specify the root dir for
  mailboxes. dbox users should migrate to ":MAILBOXDIR=mailboxes",
  because that's going to be the default in v1.2+.

+ Linux: Adding -D parameter to login_executable makes login processes
  dump core to login_dir if they crash.
- IMAP: SELECT didn't always return first unseen message in reply
- POP3: pop3_lock_session=yes didn't use mail_privileged_group while
  dotlocking.
- mbox: Don't crash if >=8192 bytes long line begins with "From ".
- Maildir: More fixes to handling over 26 keywords.
- Several logging fixes and improvements
- Fixed authentication caching with non-plaintext mechanisms when using
  a blocking passdb (e.g. MySQL)
- Fixed DIGEST-MD5 authentication with user@domain style usernames.