[Dovecot] v1.0.15 released

http://dovecot.org/releases/1.0/dovecot-1.0.15.tar.gz http://dovecot.org/releases/1.0/dovecot-1.0.15.tar.gz.sig

Still some last fixes to v1.0 series:

- IMAP: SORT SUBJECT and THREAD didn't create base subjects correctly
- Maildir: Expunged messages may have never gotten removed from
  dovecot-uidlist
- mbox: Fixed a crash when adding a new X-IMAPbase: header with
  keywords.
- Multiple "socket listen" auth blocks should have been possible, but
  Dovecot failed to start with a "With connect auth socket no other
  sockets can be used in same auth section" error.