Changes
/* Stereo sound output */
Sound chip was modified in order to get channel A+B at left, and channel B+C at right.
It was tested OK using [http://www.grimware.org/doku.php/documentations/software/starkos/start STarKos 1.21] sound tracker (track "Carpet")
In r005.8.14.1 STarKos does feel better using parameter "MEM_wr:slow" in OSD menu.
=== DONE: Another disk selector ===
