Remove spaces around the "%" when showing ratios.

This is not absolutely strictly according to the H98 report,
but it was suggested by Doug McIlroy

   According to the standard prelude, a list of Ratios prints like
   this: [1 % 1,1 % 2,1 % 3,1 % 4], which strongly suggests the
   grouping [1 % (1,1) % (2,1) % (3,1) % 4].

   Even standing alone outside of lists, the style is at odds with
   mathematical custom.  When did you last see 1/2 written as 1 / 2?