findRange

  Write a static method called findRange that
   takes a console Scanner as a parameter and that prompts the user for a
   sequence of integers, reporting the greatest difference among the integers.
   The method should prompt for integers until the user enters a 0 and it
   should then report the greatest difference between a pair of numbers from
   the sequence (i.e., the largest value for x - y where x and y are numbers
   from the sequence).  For example, the following call:

        Scanner console = new Scanner(System.in);
        findRange(console);

   would generate an interaction like this:

	number (0 to quit)? 45
        number (0 to quit)? 3
	number (0 to quit)? 8
	number (0 to quit)? 54
	number (0 to quit)? 0
	range = 51

   You must exactly reproduce the format of this sample execution.  The method
   reports 51 as the range because the greatest difference between two of these
   numbers is obtained when you take 54 minus 3.  Notice that the sentinel
   value of 0 is not considered part of the sequence.  The sequence might
   include negative values, as in the following interaction:

        number (0 to quit)? 8
        number (0 to quit)? -17
        number (0 to quit)? 5
        number (0 to quit)? 0
        range = 25

   The method reports a range of 25 because the greatest difference is obtained
   by taking 8 minus -17.  You may assume that the user types at least two
   nonzero values.  The range would be 0 if all numbers in the sequence are
   the same.