[Dovecot] 1.0-test7

http://dovecot.org/test/

Lots of bugfixes related to syncing. There's still some left.

Somewhat working mbox support:

• combined syncing/rewriting uses much less disk I/O than with older mbox code
• expunges aren't working yet
• last-uid field in X-IMAPbase header isn't updated
• it's currently syncing the whole mbox constantly even if it hasn't changed
• it isn't hiding the mbox-specific headers from IMAP clients
• if mbox hasn't changed, rewriting could start from the message which requires rewriting instead of syncing the whole mbox
• syncing could keep the lock file extra two seconds to make sure if someone changes it the file's mtime changes -> as long as only Dovecot is modifying it, we'll never need to sync the whole mbox -> multi-gigabyte mboxes are still fast!

One nice thing about this mbox code is that it isn't exactly mbox-specific. Some people are still using formats which use eg. ^A as separator rather than From-line. Some people are using SMTP-formatted data directly ('.' as mail separator, '..' = normal line begins with '.'). These formats should be pretty easy to implement now as all mbox-specific code is in istream-raw-mbox.c file. I'll probably do that once mbox itself is fully working.