Bug 3482 Allow hold notices to be sent in print form

Bug 3482 Allow hold notices to be sent in print form

This is done by saving the notices in the message_queue table with
type 'print'. The notices are generated from a notice named
HOLD_PRINT. At the end of the day, they are dumped to an HTML file and
marked as sent by a new cronjob.

This setup is intended to be temporary; modules/batch/ shouldn't be around
forever.

Mandatory SQL:
INSERT INTO message_transport_types (message_transport_type) values ('print');