std.range.iota enhancement: supporting more types (AKA issue 10762)

[Jakob Ovrum]

On Saturday, 28 December 2013 at 16:30:27 UTC, Joseph Rushton 
Wakeling wrote:
> I can see the case for it, but to me it seems like a too 
> restrictive requirement.

Yes, I can totally see that. I'm not really invested either way, 
because while I see a need for bidirectionality with `iota(start, 
end)`, it seems less useful with `iota(start, end, step)`.