bug#51733: 27.1; Detect impossible email addresses better

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 51733@debbugs.gnu.org,  jidanni@jidanni.org
> Date: Mon, 17 Jan 2022 18:09:19 +0100
> 
> I think the Unicode people have the authoritative say here, so
> implementing the recommendations seems like the way to go.  And it's
> less work in the long run, because we can just import the data files and
> not try to fix things up manually (like blocks.awk attempts to do).

Let's at least call this something other than "script", to avoid
confusion.