Charset changes pushed to CVS

[Bron Gondwana]

Hi All,

I've pushed the characterset handling changes to CVS.  They solve
all my remaining bugs in bugzilla, and are a joy to work with :)
They've been running on the Fastmail servers for about 6 months
happily.

This brings full UTF8 support to sieve scripts, charset decoding
of fields for comparision, and much better handling of whitespace
in search terms.

You will need to do a reconstruct before these changes work with
search.  In particular, a search for "foo bar" will fail to find
it without the reconstruct.  A workaround is to search for 
'or "foobar" "foo bara'" which will find both old instances where 
spaces were squashed AND new instances where they weren't!

I've also committed the user_folder_limit option, and a couple of
minor bugfixes.

Still pending is the CRC32 changeset.  We've been very happy with
it in production on our machines.  The only downside is that openssl
is required.  I'd like to have our own CRC32 implementation embedded
in the code as well, but haven't got around to massaging the public
domain one to suit yet!

Bron.