VS-1680: AUTOMIX Buttons (Special Key Operations)

Tags: vs-1680
The following list of functions can be performed by pressing multiple buttons
in conjunction with the AUTOMIX button.

AUTOMIX + TAP: Execute Snapshot (when Automix is "on")
AUTOMIX + PREVIOUS: Gradation to mixer setting of previous marker (when Automix
is "on")
AUTOMIX + NEXT: Gradation to mixer setting of next marker (when Automix is "on")
AUTOMIX + REC: Automix Realtime recording (when Automix is "on")