* 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* Remove outdated TODO/XXX
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