simplify the synchronization with Trollius

Patch provided by Berker Peksag.

Patch by Matti Picus.

Berker Peksag (already present in Misc/ACKS). The issue was reported by Brad
Aylsworth.

with ignore case.  Original patch by Matthew Barnett.

binary mode is specified.  Patch by Sam Kimbrel.

None: RuntimeError("sys.stderr is None") instead of AttributeError("'NoneType'
object has no attribute 'fileno'").

Patch written by Brad Aylsworth.

Patch by Akira.

to fully cover its state space.

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

* Repair the broken link to norobots-rfc.txt.

* HTTP response codes >= 500 treated as a failed read rather than as a not
found.  Not found means that we can assume the entire site is allowed.  A 5xx
server error tells us nothing.

* A successful read() or parse() updates the mtime (which is defined to be "the
  time the robots.txt file was last fetched").

* The can_fetch() method returns False unless we've had a read() with a 2xx or
4xx response.  This avoids false positives in the case where a user calls
can_fetch() before calling read().

* I don't see any easy way to test this patch without hitting internet
resources that might change or without use of mock objects that wouldn't
provide must reassurance.

contains characters not encodable to the stdout encoding.

argument and without current frame (ex: embedded Python).

example

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