std.range.chunk without length

[bearophile]

Stephan Schiffels:

> It would be actually easy to implement chunks without the 
> "save" function, by using an internal buffer, which would 
> however make this algorithm's memory burden linear in the chunk 
> size. Would that be acceptable?

I think it's acceptable. But perhaps you need to add one more 
optional argument for the buffer :-)

Bye,
bearophile