[Dovecot] rc13 soon

I think I'll just start making new releases whenever I've fixed something important. You'll have a while to report more bugs and then I'll make rc13 release, maybe in about 5 hours or maybe tomorrow.

I updated already the nightly snapshot if you want to test the upcoming rc13.

Changes so far:

+ deliver: If we're executing as a normal system user, get the HOME
  environment from passwd if it's not set. This makes it possible to
  run deliver from .forward.
- Older compilers caused LDAP authentication to crash
- Dying LDAP connections weren't handled exactly correctly in rc11,
  although it seemed to work usually
- Fixed crashes and memory leaks with AUTHENTICATE command
- Fixed crashes and leaks with IMAP/POP3 proxying