Libtorrent

* fix issue with web seed connections when they close and re-open
* fallocate() not supported is not a fatal error
* fix proxying of IPv6 connections via IPv4 proxy
* treat CGNAT address range as local IPs
* add stricter checking of piece layers when loading torrents
* add stricter checking of v1 and v2 hashes being consistent
* cache failed DNS lookups as well as successful ones
* add an i2p torrent state to control interactions with clear swarms
* fix i2p SAM protocol parsing of quoted messages
* expose i2p peer destination in peer_info
* fix i2p tracker announces
* fix issue with read_piece() stopping torrent on pieces not yet downloaded
* improve handling of allow_i2p_mixed setting to work for magnet links
* fix web seed request for renamed single-file torrents
* fix issue where web seeds could disappear from resume data
* extend save_resume with additional conditional flags
* fix issue with retrying trackers in tiers > 0
* fix last_upload and last_download resume data fields to use posix time
* improve error messages for no_connect_privileged_ports, by untangle it from the port filter
* fix I2P issue introduced in 2.0.0
* add async tracker status query, post_trackers()
* add async torrent status query, post_status()
* support loading version 2 of resume data format
* fix issue with odd piece sizes
* add async piece availability query, post_piece_availability()
* add async download queue query, post_download_queue()
* add async file_progress query, post_file_progress()
* add async peer_info query, post_peer_info()

* 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

* fix issue in use of copy_file_range() on linux
* avoid open-file race in the file_view_pool
* fix issue where stop-when-ready would not close files
* fix issue with duplicate hybrid torrent via separate v1 and v2 magnet links
* added new function to load torrent files, load_torrent_*()
* support sync_file_range() on linux
* fix issue in write_torrent_file() when file size is exactly piece size
* fix file_num_blocks() and file_num_pieces() for empty files
* add new overload to make_magnet_uri()
* add missing protocol version to tracker_reply_alert and tracker_error_alert
* fix privilege issue with SetFileValidData()
* add asynchronous overload of torrent_handle::add_piece()
* default to a single hashing thread, for full checks
* Fix bug when checking files and the first piece is invalid

* fix issue creating a v2 torrent from torrent_info containing an empty file
* make recheck files also update which files use partfile
* add write_through disk_io_write_mode, which flushes pieces to disk immediately
* improve copy file function to preserve sparse regions (when supported)
* add function to truncate over-sized files part of a torrent
* fix directory creation on windows shared folders
* add flag to make add_files() not record file attributes
* deprecate (unused) allow_partial_disk_writes settings
* fix disk-full error reporting in mmap_disk_io
* fixed similar-torrents feature for v2 torrents
* fix potential unbounded recursion in add_completed_job, in disk I/O
* deprecated (unused) volatile_read_cache setting
* fix part files being marked as hidden on windows

* on windows, explicitly flush memory mapped files periodically
* fix build with WolfSSL
* fix issue where incoming uTP connections were not accepted over SOCKS5
* fix several issues in handling of checking files of v2 torrents, esp. from magnet links
* make the token limit when parsing metadata from magnet files configurable
* fix issue with stalled pieces on disk full errors
* fix missing python binding for file_progress_flags
* fix torrent_file_with_hashes() to fail when we don't have the piece layers
* restore path character encoding conversion for non UTF-8 locales on linux
* fix use-after-free bug in make_magnet_uri
* add write_torrent_file() to produce a .torrent file from add_torrent_params
* allow loading v2 .torrent files without piece layer
* fix issue with adding v2 torrents with invalid file root hash

* fix piece picker bug causing double-picks with prefer-contiguous enabled
* expose session_params in python bindings
* fix (deprecated) use of add_torrent_params::info_hash
* fix issue creating and loading v2 torrents with empty files. Improves
conformance to BEP52 reference implementation