Real.toString

[Henry Cejtin]

I  was testing out the Red Hat 6.x RPMs I made of the latest MLton and wanted
to make sure that the bug Anoq found was fixed.  It was, but I see  that  our
Real.toString  has  no  decimal  points at all if the argument is an integer.
This is probably a bad idea, and doesn't match what SML/NJ does.  (The  basis
documentation seems to allow this though.)

The  %g format indicates that it only includes a decimal point if there is at
least one digit to the right of it, which is the reason that no decimal point
appears  in our output.  Short of testing and doing horrible things by hand I
have no solution.

On a more serious note, the Real.fmt function is not at all thread safe.   (I
REALLY HATE THREADS.)

I think that this function was already on the list for me to fix.