Re: master ce63f91025: Add textsec functions for verifying email addresses

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: luangruo@yahoo.com,  emacs-devel@gnu.org
> Date: Thu, 20 Jan 2022 13:46:24 +0100
> 
> > We could try appending some representative text to the string being
> > tested, of course.  For example, append a fixed string like this:
> >
> >    a1א:!
> >
> > and see if the function returns non-nil position that points to one of
> > those characters; if so, consider the original string "unsafe".
> >
> > Would that be good enough for textsec purposes?
> 
> Sounds good to me.  It should probably be baked into its own utility
> function, so that other people that wonder about strings they have
> doesn't have to know anything about these things.

Now done, see the new function textsec-bidi-controls-suspicious-p.
Feel free to tweak as needed, if the API is not convenient.