[Spambayes] pop3proxy message expiry

[Meyer, Tony]

WARNING: I've just checked in a change that will effect all pop3proxy
users.  Previously, only those messages that you had trained as spam/ham
were expired from the cache that pop3proxy keeps.  Untrained messages
were kept until they were trained.

This is no longer the case.  *ALL* messages are expired after whatever
time you have set (7 days by default).

You also no longer need to restart the proxy (or change the options) in
order to have messages expired.  Messages are expired (if old enough)
each time a mail client connects to the proxy.

Please let me know if there are any problems with this and I'll deal
with them ASAP.

=Tony Meyer