INT B3 - ZIPKEY - LOOK UP ZIPCODES FOR A GIVEN CITY                             
	AH = 79h
	BL = ZIPKEY state code of first state to search
	DS:SI -> city name, terminated with 0Dh if complete name, 00h if prefix
Return: AL = ZIPKEY state code of first matching state
	BH = number of matching entries (set to 51 if more than 50)
	DX = zipcode region of first match (0-999)
	CL = last two digits of first zipcode in first range (0-99)
	CH = last two digits of last zipcode in first range (0-99)
Note:	to find all matching cities, repeat search with BL set to one more than
	  the returned AL
SeeAlso: AH=78h,AH=7Ah