Another possible solution to the global scope debacle

[jeff.bezanson]

@StefanKarpinski

I think I prefer (2) myself, but @jeff.bezanson had compelling reasons for (1) which I can’t recall at the moment. Perhaps he can refresh my memory.

Currently for loops behave like “repeated let” — they’re exactly like let blocks but with a backwards branch. So continuing to treat them the same feels like fewer special cases to me.