1.2.3 release
- fix erroneous event=completed tracker announce when checking files
- promote errors in parsing listen_interfaces to post listen_failed_alert
- fix bug in protocol encryption/obfuscation
- fix buffer overflow in SOCKS5 UDP logic
- fix issue of rapid calls to file_priority() clobbering each other
- clear tracker errors on success
- optimize setting with unlimited unchoke slots
- fixed restoring of trackers, comment, creation date and created-by in resume data
- fix handling of torrents with too large pieces
- fixed division by zero in anti-leech choker
- fixed bug in torrent_info::swap