[Ham-Mac] Squelch

[Volker Schroer]

The squelch has two tasks:

to  keep away garbage from your screen

to show the quality of signal.

If squelch is on you can change the threshold for displaying characters
by moving the slider.

If the white bar is above the slider the characters will be displayed
otherwise they are thrown away.

On linux the bar changes it's color if the quality of the signal exceeds
the threshold, but that does not work on Mac OS X, though it's the same
code. I suppose that 's due to qt. As it's a minor problem I'll have
look on it later.

Volker