Low Latency Beeps and Clicks

[Graeme Gregory]

For future products I was wondering if we should connect a PWM GPIO to
one of the spare inputs on the wm8753 (level corrected of course).

One of the main problems the gtk+ software had with sound was making the
screen clicks happen at some time near the screen press. I think we also
probably want the ability to error beep without starting the whole
sound system.

This would give us cheap and nasty beeps and clicks without the latency
of starting the sound system each time.

It worked for Sinclair for 5 years, Im sure it can work for us.

Graeme