INT 16 - K3PLUS v6.22+ - SET KEYCLICK                                           
	AH = 04h
	AL = keyclick state
	    00h keyclick off, leave loudness setting unchanged
	    01h keyclick on, leave loudness setting unchanged
	    else
	       bit 0: keyclick enabled if set
	       bits 7-1: new keyclick loudness (non-zero)
Return: AH destroyed by many BIOSes
Note:	Applications which try to set a new loudness, but are unsure of the
	  results of other INT 16/AH=04h implementations, should set the new
	  loudness first, and then call this function again with AL=01h or
	  AL=00h
SeeAlso: AH=03h,AH=04h"KEYBOARD",AX=AF4Dh