Patch by Marc Abramowitz.

* PipeHandle now uses None instead of -1 for a closed handle
* Sort imports in windows_utils.
* Fix test_events on Python older than 3.5. Skip SSL tests on the
  ProactorEventLoop if ssl.MemoryIO is missing
* Fix BaseEventLoop._create_connection_transport(). Close the transport if the
  creation of the transport (if the waiter) gets an exception.
* _ProactorBasePipeTransport now sets _sock to None when the transport is
  closed.
* Fix BaseSubprocessTransport.close(). Ignore pipes for which the protocol is
  not set yet (still equal to None).
* TestLoop.close() now calls the close() method of the parent class
  (BaseEventLoop).
* Cleanup BaseSelectorEventLoop: create the protocol on a separated line for
  readability and ease debugging.
* Fix BaseSubprocessTransport._kill_wait(). Set the _returncode attribute, so
  close() doesn't try to terminate the process.
* Tests: explicitly close event loops and transports
* UNIX pipe transports: add closed/closing in repr(). Add "closed" or "closing"
  state in the __repr__() method of _UnixReadPipeTransport and
  _UnixWritePipeTransport classes.

waiter is cancelled before setting its exception.

cancelled before setting its exception.

* Add unit tests for this case.
* Cleanup also sslproto.py

* If an exception is raised during the creation of a subprocess, kill the
  subprocess (close pipes, kill and read the return status). Log an error in
  such case.
* Fix SubprocessStreamProtocol.connection_made() to handle cancelled waiter.
  Add unit test cancelling subprocess methods.

- Add a new _wakeup_waiter() method
- Replace _create_waiter() method with a _wait_for_data() coroutine function
- Use the value None instead of True or False to wake up the waiter

The new SSL implementation is based on the new ssl.MemoryBIO which is only
available on Python 3.5. On Python 3.4 and older, the legacy SSL implementation
(using SSL_write, SSL_read, etc.) is used. The proactor event loop only
supports the new implementation.

The new asyncio.sslproto module adds _SSLPipe, SSLProtocol and
_SSLProtocolTransport classes. _SSLPipe allows to "wrap" or "unwrap" a socket
(switch between cleartext and SSL/TLS).

Patch written by Antoine Pitrou. sslproto.py is based on gruvi/ssl.py of the
gruvi project written by Geert Jansen.

This change adds SSL support to ProactorEventLoop on Python 3.5 and newer!

It becomes also possible to implement STARTTTLS: switch a cleartext socket to
SSL.

Pass explicitly the event loop to StreamReaderProtocol.

Close the IocpProactor before closing the event loop. IocpProactor.close() can
call loop.call_soon(), which is forbidden when the event loop is closed.

Patch by Karan Goel.

reference to the selector mapping to break a reference cycle. Initial patch
written by Martin Richard.

Patch by Davin Potts.

Issue #21902: Replace incorrect 'hyperbolic arc sine' (etc.) with 'inverse hyperbolic sine' (etc.).  Remove meaningless reference to radians.

(currently only used for builds with <= 10.5 deployment targets)

Richard.

* Tulip issue 184: FlowControlMixin constructor now get the event loop if the
  loop parameter is not set. Add unit tests to ensure that constructor of
  StreamReader and StreamReaderProtocol classes get the event loop.
* Remove outdated TODO/XXX

* Document why set_result() calls are safe
* Cleanup gather(). Use public methods instead of hacks to consume the
  exception of a future.
* sock_connect(): pass directly the fd to _sock_connect_done instead of the
  socket.

Patch by A.M. Kuchling.

- clarified the distinction between text encodings and other codecs
- clarified relationship with builtin open and the io module
- consolidated documentation of error handlers into one section
- clarified type constraints of some behaviours
- added tests for some of the new statements in the docs

availability of the function is checked during the compilation. Patch written
by Bernard Spil.

ssl.PROTOCOL_SSLv23 protocol by default, not ssl.PROTOCOL_SSLv3, for maximum
compatibility and support platforms where ssl.PROTOCOL_SSLv3 support is
disabled.

the waiter future before setting its result.