Changes:
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
