Add strategy for Internet Archive torrents

[nemobis]

The Internet Archive has over 50 million torrent files for as many items.

The trackers are:

• http://bt1.archive.org:6969/announce
• http://bt2.archive.org:6969/announce

The archive.org servers themselves don't seed the torrents over bittorrent, they only provide web seeds. Few torrents will have any seeders at all, but a few have leechers. It would be nice to be able to search the most active ones. Some of the most included torrents include audio or video

You can get the info_hash list from the "btih" field inside the "files" field of the XML metadata of each item, or in JSON with the internetarchive Python utility, ofr instance:

ia search -i "format:bittorrent -format:warc -format:arc -access-restricted-item:true" | xargs -P4 -I§ sh -c "ia metadata § | jello -rl '\
result=[f.btih for f in _.files if f.name.endswith(\"archive.torrent\")]
result' " > ia_all_torrents_btih.txt