Issue22506: added methods on base Enum class now show up in dir of Enum subclass (3.4)

--HG--
branch : 3.4
Issue22506: merge from 3.4
Issue #18643: Add socket.socketpair() on Windows.
Issue #18643: asyncio.windows_utils now reuse socket.socketpair() on Windows if
available

Since Python 3.5, socket.socketpair() is now also available on Windows.

Make csock blocking before calling the accept() method, and fix also a typo in
an error message.

--HG--
branch : 3.4
extra : rebase_source : 3395285d7d9d4f66966dd2a95812548821a46cf5
Issue #22632: replace dead link with version-specific doc link.

--HG--
branch : 3.4
Merge with 3.4
Merge 3.4 (asyncio)
Issue #20152: Convert the cmath module to Argument Clinic.
Issue #3068: Change 0/1 to False/True so that extension configure dialog can
easily recognize and display boolean values as such and recognize changes.
Also reformat comments and alphabetize extensions included with Idle.

--HG--
branch : 3.4
Merge with 3.4 #3068