[Dovecot] 1.0.beta6 released

Fixes, mostly:

* The login and master usernames were reversed when using
  master_user_separator (now the order is UW-IMAP compatible).
* Killing dovecot master process now kills all IMAP and POP3
  processes also.

+ -a parameter to dovecot prints now all settings that Dovecot uses.
  -n prints all settings that are different from defaults.
+ Added pop3_lock_session setting
+ %M modifier returns string's MD5 sum. Patch by Ben Winslow
- PLAIN SASL authentication wasn't working properly, causing failed
  logins with some clients (broken in beta4)
- Fixes to Maildir++ quota, should actually work now
- Don't crash if passwd-file has entries without passwords
  (eg. deny=yes databases)
- Fixed prefetch userdb to work nicely with other userdbs
- If master process runs out of file descriptors, don't go to
  infinite loop (unlikely to have happened unless the OS's default
  fd limit was too low)
- Fixed non-plaintext password lookups from LDAP. Patch by Lior Okman
- %U modifier was actually lowercasing the string. Patch by Ben Winslow