[bug][fix] range of single value gets divide-by-zero exception

[Tim Olson]

(1 to: 1).

returns a divide by zero exception because the code to set the 
appropriate increment value uses the <=> message, which returns 0 when 
its operands are equal.  The fix is to explicitly use 1 or -1:

r@(Range traits) newFrom: start to: end
"This method implicitly defines a sensible default stepping value."
[
   r newFrom: start to: end by: (start <= end ifTrue: [1] ifFalse: [-1])
].


	-- Tim Olson