Don't allow replies to messages with the "NoReply" attribute set.

Don't prompt for "delete mail from everyone" when there is only one e-mail
waiting for the user.
Use some existing text.dat entries (some old and some recently added) where
identical static strings were still being used for no apparent reason.
Added several text.dat entries for the QWK settings menu, node status, and
some other single-line messages (replacing static strings).