Remove spaces from output of toString so as to match other languages.

Python, Haskell etc. display rationals in the form

   1/2, 2/3, 3/4, 4/5, ...

and not

   1 / 2, 2 / 3, 3 / 4, 4 / 5, ...

which is also less easy to read in practice.
Use LINK2 for external link.