add TFTP service
change RemoteTorrentHandler to use TFTP
change code that uses download_torrent() of RemoteTorrentHandler
change Session download_torrentfile() and download_torrentfile_from_peer() and code that uses them
create RemoteTorrentHandler unit test
remove SwiftEndpoint
simplify TFTP and make TFTP queue
change SearchCommunity to v2
disable fallback magnet download
RemoteTorrentHandler cleanup
create tarball for directories using TFTP
change metadata to use TFTP
add metadata download test