libtorrent 1.2.1

1.2.1 release

• add dht_pkt_alert and alerts_dropped_alert to python bindings
• fix python bindins for block_uploaded_alert
• optimize resolving duplicate filenames in loading torrent files
• fix python binding of dht_settings
• tighten up various input validation checks
• fix create_torrent python binding
• update symlinks to conform to BEP 47
• fix python bindings for peer_info
• support creating symlinks, for torrents with symlinks in them
• fix error in seed_mode flag
• support magnet link parameters with number siffixes
• consistently use "lt" namespace in examples and documentation
• fix Mingw build to use native cryptoAPI
• uPnP/NAT-PMP errors no longer set the client's advertised listen port to zero