* Fix ResourceWarning warnings in test_streams
* Return True from StreamReader.eof_received() to fix
  http://bugs.python.org/issue24539 (but still needs a unittest).
  Add StreamReader.__repr__() for easy debugging.
* remove unused imports
* Issue #234: Drop JoinableQueue on Python 3.5+

* queues: get coroutine from asyncio.coroutines, not from asyncio.tasks
* tets: replace tulip with asyncio in comments

tests: Remove unused function; inline another function

* Tulip issue 184: FlowControlMixin constructor now get the event loop if the
  loop parameter is not set. Add unit tests to ensure that constructor of
  StreamReader and StreamReaderProtocol classes get the event loop.
* Remove outdated TODO/XXX

Fix test-order-dependend asyncio test failure caused by rev 909ea8cc86bbab92dbb6231668f403b7360f30fa.

asyncio: Fix upstream issue 168: StreamReader.read(-1) from pipe may hang if data exceeds buffer limit.

Use "from unittest import mock". It should simplify my work to merge new tests
in Trollius, because Trollius uses "mock" backport for Python 2.

Thanks to Vajrasky Kok for discovering some of them.

Thanks to Vajrasky Kok for discovering some of them.

Major changes:

- StreamReader.readexactly() now raises an IncompleteReadError if the
  end of stream is reached before we received enough bytes, instead of
  returning less bytes than requested.

- Unit tests use the main asyncio module instead of submodules like events

- _UnixWritePipeTransport now also supports character devices, as
  _UnixReadPipeTransport. Patch written by Jonathan Slenders.

- Export more symbols: BaseEventLoop, BaseProactorEventLoop,
  BaseSelectorEventLoop, Queue and Queue sublasses, Empty, Full