INT 31 - CauseWay - "GetSel" - ALLOCATE NEW SELECTOR

	AX = FF03h
Return: CF clear if successful
	    BX = new selector
	CF set on error
Note:	the new selector is initialized with a base address of 000000h, a limit
	  of 0000h, and attributes read/write expand-up data
SeeAlso: AX=FF04h,AX=FF05h,AX=FF06h