Greyfix 0.4.0 release candidate 2

[Kim Minh Kaplan]

Hello,

I have prepared a release candidate for Greyfix. You can get it from
<https://www.kim-minh.com/pub/greyfix>.

* The major underlying change are in the database handling.

* Greyfix now uses Berkeley DB's transactionnal mecanism. It can thus
automatically recover the database upon failure.

* The database format has changed. Greyfix will automatically upgrade
from the old format to the new format. Note that you can *not*
downgrade back to the old format. So backup your database if you
consider rolling back.

* A new option, --network6-prefix, as been added. It is similar to
--network-prefix, but for IPv6 address. Now that some major players
are using IPv6 mail farms to send out email, this is a must.

* Some signal handling woes were fixed.

Please report your experience with it, especially regarding the
automatic database upgrade and IPv6 handling.
--
Kim Minh