limiting number of HTTP request headers

[Maksim Yevmenkin]

hello!

[...]

> Looking more into it while writing tests and docs, I tend to think
> that just "max_headers" would be enough, similarly to
> "ignore_invalid_headers" and "underscores_in_headers".
>
> Mostly identical patch below (s/max_client_headers/max_headers/),
> as well as tests and docs.  I'm going to commit these shortly
> unless there are objections.
>
> Thanks for prodding this!

no objections, thank you!

max