libtorrent-2.0.8

changes since previous 2.0.x release:

• fix uTP streams timing out instead of closing cleanly
• add write_torrent_file_buf() overload for generating .torrent files
• add create_torrent::generate_buf() function to generate into a buffer
• fix copy_file when the file ends with a sparse region
• uTP performance, fix packet loss when sending is stalled
• fix trackers being stuck after session pause/resume
• fix bug in hash_picker with empty files
• uTP performance, prevent premature timeouts/resends
• add option to not memory map files below a certain size
• settings_pack now returns default values when queried for missing settings
• fix copy_file fall-back when SEEK_HOL/SEEK_DATA is not supported
• improve error reporting from file copy and move
• tweak pad file placement to match reference implementation (tail-padding)
• uTP performance, more lenient nagle's algorithm to always allow one outstanding undersized packet
• uTP performance, piggy-back held back undersized packet with ACKs
• uTP performance, don't send redundant deferred ACKs
• support incoming SOCKS5 packets with hostnames as source address, for UDP trackers
• ignore duplicate network interface change notifications on linux
• fix total_want/want accounting when forcing a recheck
• fix merging metadata with magnet links added on top of existing torrents
• add torrent_flag to default all file priorities to dont_download
• fix &so= feature in magnet links
• improve compatibility of SOCKS5 UDP ASSOCIATE
• fix madvise range for flushing cache in mmap_storage
• open files with no_cache set in O_SYNC mode