the default exception/value when called instead of raising/returning
NotimplementedError/NotImplemented (except where appropriate).
This should allow for the ABCs to act as the bottom/end of the MRO with expected
default results.

As part of this work, also make importlib.abc.Loader.module_repr()
optional instead of an abstractmethod.

>>> import asyncore
>>> d = asyncore.dispatcher()
>>> d.close()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.4/asyncore.py", line 401, in close
    self.socket.close()
AttributeError: 'NoneType' object has no attribute 'close'
>>>

usage of get_origin_req_host() to origin_req_host.

Patch by Wei-Cheng Pan

of get_origin_req_host() to origin_req_host.

Patch by Wei-Cheng Pan

expansion.

Patch by Todd Rovito.

wmemcmp() is twice faster than a dummy loop (342 usec vs 744 usec) on Fedora
18/x86_64, GCC 4.7.2.

Kinds: ascii, latin, bmp, astral.

write specialized functions for each combination of Unicode kinds.

Patch by Thomas Fenzl.

efficient machine code. Patch written by Antoine Pitrou.

Without this change, str.find() was 10% slower than str.rfind() in the worst
case.

Patch by Michael Ford.

Patch by Michael Ford.