1. Added msg command to allow the changing of To, From, Subject and so on the

1. Added msg command to allow the changing of To, From, Subject and so on the
messages. This seems particularly important just now as a whole raft of G3's
seem to be putting out non private bulls to callsigns.
2. While I am at set messages to TO fields that appear to be users to private
if they have been sent as bulls.
3. Add DISTROs, if a callsign field appears in /spider/msg/distro in upper
use that as a list of callsigns to send further. Note this is potentially
recursive as callsigns in a distro can be distros.