Merge pull request #421 from minrk/changes14

start changes for 14.0
bundle libzmq-4.0.1
link libsodium if available in bundled libzmq
rename stopwatch to utils in cython backend

place to put everything from zmq_utils.h
expose zmq.curve_keypair

in Cython backend
add curve_keypair to cffi
curve_keypair docstrings
test curve_keypair
Merge pull request #424 from minrk/4.1

updates for zmq 4.0
update version_info

semver-style always 3 ints, dev is 4th entry, if any
pass on utils docs
monitor fixup
pass on core zmq docs
pass on device docs
index pass
import zmq for docs version
changelog for 14.0