Make transaction CFs correctly limited to the correct queues

In 74e6f62, the $queues{...}++ line was moved from above the "next
unless ..." line to below it.  This changes the meaning of %queues, from
"the set of queues of the tickets listed" to "the set of queues of
tickets _changed_."  This causes the transaction CF list to be broader
than expected in most cases.

Make the transaction CFs limited based on $seen_queues, which is
computed based on all tickets listed, and remove the no-longer-used
%queues.
Don't output to STDOUT for successfully sent digests, by default

Most commonly, digests are sent from cron jobs, where any output to
STDOUT is sent to the administrator.  Printing on every successfully
sent digest will thus lead to the administrator getting sent daily mail
which is essentially content-less.  This might lead them to redirect the
output to /dev/null, which would cause them to be ignorant when sending
messages _failed_.

Restrict output to STDOUT to only when messages failed to send, by
default.  The new --verbose option can be used to restore the old
behavior of printing for every message sent.
Merge branch '4.0/digests-no-mail-on-success' into 4.0-trunk
Merge branch '4.0/transaction-cf-limit-on-bulk-update' into 4.0-trunk