I wasn't able to find a equivalent in curl with a very cursory search, but wget has `--page-requisites`, which fetches (nominally) every file needed to display

I wasn't able to find a equivalent in curl with a very cursory search, but wget has `--page-requisites`, which fetches (nominally) every file needed to display a HTML document. If curl does have something analogous, this change would allow html of the form: <img src="ipfs://WHATEVER"/> to be handled transparently (even when it occurs in a page that is not itself on IPFS). Ideally similar support would be added for "magnet:?..." and "[...].onion/..." URLs, for the same reason.