Merge pull request #661 from lalebarde/master

simplify test_security_curve.cpp with zmq_z85_encode
Fix windows build
Merge pull request #662 from ricnewton/master

Fix windows build
Fixed random failures in test_security_plain and _curve

* ZAP handler thread was not getting time to start up
* Code now creates and binds handler socket in parent thread and
  passes the socket to the zap_handler, so this always gets the
  authentication requests.
Merge pull request #663 from hintjens/master

Fixed random failures in test_security_plain and _curve
NULL mechanism was not dealing with ZAP denials properly
Merge pull request #664 from hintjens/master

NULL mechanism was not dealing with ZAP denials properly
Added test case for NULL domains
Fixed length of domain setting
Merge pull request #665 from hintjens/master

Added test case for NULL domains
makes curve keys symetric as in libcurve + factorisation
oblige the application to explicitely set the node type for PLAIN