bug#36494: 27.0.50; [Proposition] New option to scroll up regardless of eob

[Eli Zaretskii]

> From: Marco Wahl <marcowahlsoft@gmail.com>
> Cc: Marco Wahl <marcowahlsoft@gmail.com>,  36494@debbugs.gnu.org
> Date: Thu, 04 Jul 2019 23:07:15 +0200
> 
> Ok, sorry for the patch missing.  Here is the patch.

Thanks.

This seems to work well, but when there's only the single last line
visible in the window, and the cursor is at EOB, S-DOWN scrolls back,
i.e. after pressing it Emacs now shows 2 last lines.  I don't think
this is intended, is it?

Also, this is a user-visible change, so it needs to be called out in
NEWS.

Could you please resubmit with these minor nits fixed?