Libtorrent

* 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

* add new torrent_file_with_hashes() which includes piece layers for
creating .torrent files
* add file_prio_alert, posted when file priorities are updated
* fix issue where set_piece_hashes() would not propagate file errors
* add missing python binding for event_t
* add work-around for systems without fseeko() (such as Android)
* add convenience header libtorrent/libtorrent.hpp
* increase default max_allowed_in_request_queue
* fix loading non-ascii filenames on windows with torrent_info constructor (2.0 regression)
* add std::hash<> specialization for info_hash_t
* fix integer overflow in hash_picker and properly restrict max file sizes in torrents
* strengthen SSRF mitigation for web seeds

* add v1() and v2() functions to torrent_info
* fix piece_layers() to work for single-piece files
* fix python binding regression in session constructor flags
* fix unaligned piece requests in mmap_storage
* improve client_data_t ergonomics
* fix issue with concurrent access to part files