Netifaces-plus

* Fixed a problem with multi-part Netlink messages on Linux.

* When using Netlink (i.e. Linux), check for the constant
NLM_F_DUMP_INTR, since it only appeared in kernel version 3.1

* Added a workaround for broken netlink headers on certain Linux
distributions (the problem being that the netlink headers fail to
include <bits/sockaddr.h>, which causes a build failure).

* Fixed a problem with the gateways() function that caused it a
crash on PyPy.
* The CI system is now set up to build for PyPy as well, so
problems will be found sooner.

* Python 3 compatibility.
* Improved Windows source code compatibility.
* Added gateway detection via gateways() function.
* New version number format (skipped 0.9.0 due to its use by
the netifaces-merged fork).

All changes in this version relate to the ioctl( ) code path,
which is not used on Windows or on any modern UNIX or UNIX-like
system that implements getaddrinfo().

* Fixed bit-rot in the ioctl() code path.
* Fixed a problem with setup.py that might manifest itself if the
config.cache file was manually edited.
* Fixed the ioctl() code path to cope with systems that have
sa_len and return longer than normal struct ifreq requests from
SIOCG[L]IFCONF (for instance, Mac OS X).