Replication errors: missing subscription

[Bron Gondwana]

Our Cyrus 2.3.12 + patches replication system has been running very
reliably for months - to the point where the only issues our
checkreplication script tends to find are either:

a) cases where someone has reconstructed and not run quota -f
   afterwards, causing quota mismatches.  (this is mostly the
   fault of bits of our code that need updating!)

b) subscriptions missing on the replica.

I have a suspicion that most of these could be avoided by the simple
expedient of switching from putting individual subscription records
into the sync log to copying the entire user.sub file.

(I've also changed setseen_all to just overwrite the user.seen file 
rather than attempt some sort of merger.  It's a replica, the master
is right!  This will break if you're using a different database type
on the replica than the master of course - but that's why you
shouldn't be sending binary formats over the wire in the first place.
It's already going to break)

Bron.