methods created by functool.total_ordering.

Patch by Serhiy.

Reported by Damien Marié.

Reported by Damien Marié.

* Move the test for an exact key match to after a hash match
* Use "used" as a loop counter instead of "fill"
* Minor improvements to variable names and code consistency

- Move all Py_LIMITED_API exclusions together under one #ifndef
- Group PyAPI_FUNC functions and PyAPI_DATA together.
- Bring related comments together and put them in the appropriate section.

asyncio.BaseEventLoop now use the identifier of the current thread to ensure
that they are called from the thread running the event loop.

Before, the get_event_loop() method was used to check the thread, and no
exception was raised when the thread had no event loop. Now the methods always
raise an exception in debug mode when called from the wrong thread. It should
help to notice misusage of the API.

* Fix pyflakes warnings: remove unused imports and variables
* asyncio.test_support now uses test.support and test.script_helper if available

Patch by Vajrasky Kok.

The versionadded directive is already placed in the scope of the
HTTPStatus documentation.

Patch by Wojtek Ruszczewski.

Following suggestions from Clément.