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

[Gregory Heytings]

> Anyway, speaking about other faces you could inherit from (for the echo 
> area flash), how about 'highlight' instead of 'match'?
>
> Seems more appropriate.

Yes, I noted that you'd prefer to use highlight instead of match, 
presumably for a certain logical consistency.  If highlight had been 
yellow, that's what I would have done.  For this specific case I believe 
yellow is the most appropriate color.  If inheriting from highlight is not 
okay, I'd hardcode the yellow color.