* Make directory mirrors (which FetchDirInfoEarly) fetch from fallback directory mirrors, before they try authorities * Modify directory_should_fetch_from_authorities(): * move FetchDirInfoEarly to directory_fetches_dir_info_early, and make directory_fetches_dir_info_early fetch from the fallback directory mirrors * change DirPort_set to dir_server_mode() or similar (requires legacy/trac#12538) and move to directory_fetches_dir_info_early * move refuseunknown to directory_fetches_dir_info_early Directory mirrors shouldn't need a different schedule to fetch from fallback directory mirrors, they can simply fetch on their standard schedule.