SURANGE - get max and min values for non-zero header entries	

 surange <stdin	 					

 Note: gives partial results if interrupted			


 Credits:
	SEP: Stew
	CWP: Jack

 Note: the use of "signal" is inherited from BSD days and may
       break on some UNIXs.  It is dicy in that the responsibility
	 for program termination is lateraled back to the main.