Log Message:
Update to dovecot-1.0rc26.

Most importantly this should fix mbox problems in recent RCs.

	* Changed --with-headers to --enable-header-install
	* If time moves backwards only max. 5 seconds, sleep until we're back
	  in the original present instead of killing ourself. An error is
	  still logged.

	- IMAP: With namespace prefixes LSUB prefix.* listed INBOX.INBOX.
	- deliver: Ignore mbox metadata headers from the message input.
	  X-IMAP header crashed deliver.
	- deliver: If mail_debug=yes, drop out DEBUG environment before
	  calling sendmail binary. Postfix's sendmail didn't really like it.
	- mbox: X-UID brokeness fixes broke rc25 even with valid X-UID headers.
	  Now the code should finally work right.
	- Maildir: When syncing a huge maildir, touch dovecot-uidlist.lock file
	  once in a while to make sure it doesn't get overwritten by another
	  process.
	- Maildir++ quota: We didn't handle NUL bytes in maildirsize files very
	  well. Now the file is rebuilt when they're seen (NFS problem).
	- Index/view handling fix should fix some crashes/errors
	- If index files were moved to a different endianess machine, Dovecot
	  logged all sorts of errors instead of silently rebuilding them.
	- Convert plugin didn't change hierarchy separators in mailbox names.
	- PostgreSQL authentication could have lost requests once in a while
	  with a heavily loaded server.
	- Login processes could have crashed in some situations
	- auth cache crashed with non-plaintext mechanisms