[docs] Code, test, and doc review for PEP-0435 Enum (issue 17947)

[ethan at stoneleaf.us]

I'll try to have the changes in place later tonight; otherwise it will
be tomorrow.


http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst
File Doc/library/enum.rst (right):

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode240
Doc/library/enum.rst:240: of *_sunder_* names, *__dunder__* names, and
descriptors; methods are
Ah, yes.  _sunder_names_ are completely forbidden, __dunder_names__ are
only forbidden from being enum members.

I'll clarify.

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode245
Doc/library/enum.rst:245: methods.
I'll add something.

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode260
Doc/library/enum.rst:260: But this is allowed::
I'll see what I can dream up.  :)

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode280
Doc/library/enum.rst:280: A variation of :class:`Enum` is proposed which
is also a subclass of :class:`int`.
Done.

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode331
Doc/library/enum.rst:331: Other derived enumerations
Will do.

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode340
Doc/library/enum.rst:340: This demonstrates how similar derived
enumerations can be defined, for example
Done.

http://bugs.python.org/review/17947/diff/8332/Doc/library/enum.rst#newcode443
Doc/library/enum.rst:443: ...                     )
Done.

http://bugs.python.org/review/17947/diff/8332/Lib/enum.py
File Lib/enum.py (right):

http://bugs.python.org/review/17947/diff/8332/Lib/enum.py#newcode42
Lib/enum.py:42: """Returns True if a sunder name, False otherwise."""
Done.

http://bugs.python.org/review/17947/