This serves to be better documenting about what they're doing and why,
instead of having a dozen slightly different loops that each have to be
examined.

Fix #775

Fix test_socket under 3.4 with the ares resolver by handling in Python code two cases ares itself doesn't handle.

Return whether the pool became empty in join.

Useful with a timeout argument.

Fixes #503.

[skip ci]

It would become False anyway as soon as the method returned. We won't
schedule another one while it's running (True), so there's no race
condition.

Switch to using prospector for lint checks

Don't immediately run links added to an Event/AsyncResult while it is running callbacks. Fixes #771.

and document the settings.

Fixed typo error

Figured out the root cause of the u-v-a crash in https://github.com/PyCQA/pylint/issues/846: unsafe-load-any-extension causes it.

cleanup threadpool.
various small cleanups.
cleanup _fileobjectposix.

clean up resolver_ares
cleanup thread.
cleanup testrunner
cleanup pool.
clean up event