#163 Download only torrent from magnet link

[Anonymous]

If I specify magnet link and use option --bt-save-metadata aria2c download torrent and its content. But if I want only download torrent (for using it in some other client, for example) I can't say aria2c to not downloading content. Option --follow-torrent=false does'nt work in this case. Also, when saving torrent it will be very useful to add a "nodes" field with DHT peers if torrent is trackerless.

[tujikawa]

--bt-metadata-only option was added to download metadata only.
For nodes, I don't want to save IP address of someone in torrent file, so it is wont fix.