help: add new deprecated topic Add a deprecated topic which lists most of the commands and options that are not recommended anymore.

phabricator: split auth.url into the standard auth.schemes and auth.prefix It seems better to reuse the existing function to find the proper [auth] block, even if not all of the possible settings may be of interest. The other callers of readauthforuri() make a trip through the password database to fetch the user from the URI. But in the little experimenting I did here, the username always came back as None. Since readauthforuri() wants it to make sure that user@prefix matches user@url, it seems that parsing the URL and pulling out the user component should be equivalent.