env var), document the default debug mode

Add also a PYTHONASYNCIODEBUG environment variable to debug coroutines since
Python startup, to be able to debug coroutines defined directly in the asyncio
module.

Initial patch by Nick Coghlan.

On Mac OS X Tiger (and older), getsockname() returns a zero-length address for
UNIX socket, and so 'sockname' extra info is None.

exception raised by sys.exit is None when no code is given.

As suggested by Serhiy Storchaka.

Tkinter widgets to work in wantobjects=True mode.

Tkinter widgets to work in wantobjects=True mode.

of BaseEventLoop

Thanks to Vajrasky Kok for discovering some of them.

sockname, as _basetest_create_ssl_connection().

DeprecationWarning warnings. create_unix_server() closes the socket on any
error, not only on OSError.

Mention if the error was caused by a read or a write, and be more specific on
the object (ex: "pipe transport" instead of "transport").

ignores OSError(22, 'Invalid argument') when writing input data into stdin,
whereas the process already exited.

OSError(22, 'Invalid argument') when writing input data into stdin, whereas
the process already exited.

and to modernize.  Patch by Gareth Rees.

Cast from time_t (64 bit) to long (32 bit). It should fix a compiler warning.