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.

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").

OpenBSD older than 5.5

Vajrasky Kok.

also typo. Patch written by Vajrasky Kok.

- now also allows POSIX installation with SSL/TLS missing
- a goal for pip 1.6 is to allow local use without SSL/TLS

regression: don't clear anymore the state of Python threads early during the
Python shutdown.

the address is not resolved (hostname instead of an IP address) for AF_INET and
AF_INET6 address families.