Add a matching option that matches on the recorded url of a file.

My use case is eg using, git-annex find to list files that were addurled from a given host. So I want a way to match on the url with a glob, eg --url=*/example.com/*

Seems likely that there would also be a corresponding preferred content expression if adding that.

An alternative way could be to populate a metadata field with the url, if that were done without increasing the size of the git repository. --Joey

done --Joey