foreach syntax, std.mixin

[dsimcha]

== Quote from Bill Baxter (wbaxter at gmail.com)'s article
> I agree.  Those numbers don't seem so bad, particularly if inlining is
> possible in the future.
> But there's still the issue of how to get both an enumeration and an
> unpacked tuple together.
> --bb

Yeah, I thought about this, and I didn't have any good answer other than make an
absurdly baroque enumerateUnpack function.  I'd be open to suggestions here.