bug#1305: All code that currently beeps should use visual bell instead

[Gregory Heytings]

> > And AFAICS this is also what most popular starter kits do. So at least 
> > to me it's not clear whether it is widely used.
>
> better-defaults is an old project which has been there for at least a 
> decade in some form (and has a fair amount of stars on its archived 
> repository on github: https://github.com/technomancy/better-defaults). 
> It's the original "emacs starter kit".

Amusingly, it's the only "better default" that isn't described in the 
README, and against which there's a open issue: 
https://github.com/technomancy/better-defaults/issues/27 .

> A moving reddish shape should bring enough attention, but of course 
> different users have different levels of sensitivity (as the discussion 
> in bug#47574 has shown). Only a practical experiment can tell.

Moving???  Why do you think this would be better than simply blinking the 
echo area?