[Nickle] New Nickle cosmetic feature

[Bart Massey]

A common C idiom is to use the value of a for() loop index
"off-the-end":

   int x = 0;
   for (; x < 5; x++)
      foo(x);
   for (; x < 10; x++)
      bar(x);

That extra leading semicolon has always driven me nuts.
It is now optional. IMHO this is much easier to read

   int x = 0;
   for (x < 5; x++)
      foo(x);
   for (x < 10; x++)
      bar(x);

so I hacked the grammar etc to fix it.

Have fun!

	Bart