Add socket.create_server_sock() convenience function

[Charles-François Natali]

http://bugs.python.org/review/17561/diff/7717/Lib/socket.py
File Lib/socket.py (right):

http://bugs.python.org/review/17561/diff/7717/Lib/socket.py#newcode441
Lib/socket.py:441: listen for both IPv4 and IPv6 connections.
The term "dual stack" is a bit confusing: it just means that the host implements
both IPv4 and IPV6 stacks natively (i.e. you don't have to use tunnels/etc).
Here, we really want to know if it supports IPv4-mapped IPv6 addresses.
See http://tools.ietf.org/html/rfc4213

Also, I'm not convinced we need to expose this yet. We can just provide a best
effort function, someone needing precise control could create the socket
manually (and e.g. use select).

http://bugs.python.org/review/17561/diff/7717/Lib/socket.py#newcode445
Lib/socket.py:445: or not hasattr(_socket, 'IPV6_V6ONLY'):
I think PEP8 discourages line breaks using '\': parenthesis would be better IMO.

http://bugs.python.org/review/17561/diff/7717/Lib/socket.py#newcode460
Lib/socket.py:460: dual_stack=has_dual_stack()):
Same thing here, I think it complicates the signature.
Someone needing precise control can bind the socket by hand, and use select() if
necessary.

http://bugs.python.org/review/17561/diff/7717/Lib/socket.py#newcode463
Lib/socket.py:463: 
The *reuse_addr* argument is not documented in the docstring, and doesn't appear
in any other socket's method signature.
It would probably be good to add a line about it.

Also, I'm not sure it's really wise to enable SO_REUSEADDR by default: it's
practical, but it's not the default on BSD sockets.

Furthermore, having a default value different between Unix and Windows is bad
for portability.

Finally, "explicit is better than implicit" ;-)

http://bugs.python.org/review/17561/diff/7717/Lib/socket.py#newcode477
Lib/socket.py:477: AF_INET6_ = getattr(_socket, "AF_INET6", 0)
It might be possible to use socket.has_ipv6.