- util::http::*: since spool file is server provided, use option
"-spool" to indicate that spooling is intended. The actual name of
the spool file is retuned in the "file" component of the dict.
- fix spool file logic for ns_http/ns_ssl
- allow spooling as well for curl
- drop "-depth" for the toplevel interface, since it is used for
iteration on the (private) implementation level
- set max_depth per default to 10 to handle redirects automatically
