sockets are context managers
Merge pull request #594 from minrk/socket-context

sockets are context managers
update bundled extensions

- libsodium-1.0.0
- libzmq-4.0.5
Merge pull request #597 from minrk/libzmq-4.0.5

update bundled extensions
don't assign allow_interrupt.__doc__

set it in class definition,
because assignment isn't allowed on py2
Merge pull request #598 from minrk/whatsnew

changelog for 14.4.0
update constants from libzmq-4.1

adds fd_sockopts list, rather than special-casing FD
add zmq.has