Python-libtorrent

* fix string encoding in error messages
* handle error in read_piece and set_piece_deadline when torrent is removed
* DHT performance improvement
* attempt to handle ERROR_CANT_WAIT disk error on windows
* improve peers exchanged over PEX
* fixed rare crash in ut_metadata extension
* fixed files checking issue
* added missing pop_alerts() to python bindings
* fixed typos in configure script, inversing some feature-enable/disable flags
* added missing flag_update_subscribe to python bindings
* active_dht_limit, active_tracker_limit and active_lsd_limit now
interpret -1 as infinite

* fixed verbose log error for NAT holepunching
* fix a bunch of typos in python bindings
* make get_settings available in the python binding regardless of
deprecated functions
* fix typo in python settings binding
* fix possible dangling pointer use in peer list
* fix support for storing arbitrary data in the DHT
* fixed bug in uTP packet circle buffer
* fix potential crash when using torrent_handle::add_piece
* added missing add_torrent_alert to python binding

* udp socket refcounter fix
* added missing async_add_torrent to python bindings
* raised the limit for bottled http downloads to 2 MiB
* add support for magnet links and URLs in python example client
* fixed typo in python bindings' add_torrent_params
* introduce a way to add built-in plugins from python
* consistently disconnect the same peer when two peers simultaneously connect
* fix local endpoint queries for uTP connections
* small optimization to local peer discovery to ignore our own broadcasts
* try harder to bind the udp socket (uTP, DHT, UDP-trackers, LSD) to the
same port as TCP
* relax file timestamp requirements for accepting resume data
* fix performance issue in web seed downloader (coalescing of blocks
sometimes wouldn't work)
* web seed fixes (better support for torrents without trailing / in
web seeds)
* fix some issues with SSL over uTP connections
* fix UDP trackers trying all endpoints behind the hostname

* raise the default number of torrents allowed to announce to trackers
to 1600
* improve uTP slow start behavior
* fixed UDP socket error causing it to fail on Win7
* update use of boost.system to not use deprecated functions
* fix GIL issue in python bindings. Deprecated extension support in python
* fixed bug where setting upload slots to -1 would not mean infinite
* extend the UDP tracker protocol to include the request string from the
tracker URL
* fix mingw build for linux crosscompiler

* fix python binding backwards compatibility in replace_trackers
* fix possible starvation in metadata extension
* fix crash when creating torrents and optimizing file order with pad files
* disable support for large MTUs in uTP until it is more reliable
* expose post_torrent_updates and state_update_alert to python bindings
* fix incorrect SSL error messages
* fix windows build of shared library with openssl
* fix race condition causing shutdown hang

* fix permissions issue on linux with noatime enabled for non-owned files
* use random peer IDs in anonymous mode
* fix move_storage bugs
* fix unnecessary dependency on boost.date_time when building boost.asio as separate compilation
* always use SO_REUSEADDR and deprecate the flag to turn it on
* add python bindings for SSL support
* minor uTP tweaks
* fix end-game mode issue when some files are selected to not be downloaded
* improve uTP slow start
* make uTP less aggressive resetting cwnd when idle