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

[Gregory Heytings]

> > > So in this instance, defaulting `visible-bell' to "on" would make 
> > > `C-g' more intrusive/obnoxious than previously...  which is the 
> > > opposite effect than what was originally discussed in this bug report.
> >
> > Can anything be done about that, though?
>
> I think this might point toward not doing anything about the default -- 
> people who don't like beeps will switch them off on the OS level.  That 
> is, flipping the default will make `C-g' more intrusive for people 
> who've already made a decision to ignore beeps.

Note that for GNU/Linux users who use a more exotic window manager instead 
of Gnome or KDE, it's the opposite: they have to make an active decision 
to hear beeps.  IOW, they will not hear any beep unless they configure 
their computer to do so.

I checked on macOS, and the only apps (at least, the only apps among the 
ones I use) that repeatedly beep are the terminal and Emacs.  Other apps 
only beep when you do something "wrong", that is, when they cannot do what 
you want (for example when you ask the program to paste something when 
there is nothing to paste), or when they open an important dialog.  The 
terminal also beeps when it cannot do what you want (for example when you 
press TAB and it cannot complete the current input).  In comparison, Emacs 
beeps a lot.