Update to 1.3.1

* Enable SASL support

Changelog:
This is a long overdue maintenance release:
- SSL now uses SNI, which for example GMail requires
- fixed fallbacks for missing UIDPLUS extension (with e.g. DavMail)
- fixed UIDVALIDITY recovery with really long Message-id headers
- fixed GSSAPI authentication with Kerberos
- fixed support for IMAP servers which do not sort search results (e.g.,
  poczta.o2.pl)
- fixed CopyArrivalDate on platforms without glibc
- fixed useless SASL warnings with certain plugins
- the perl 5.14 requirement is now made explicit
- improved OpenBSD support
- fixed a bunch of compiler warnings

(ryoon)