Release v0.7.0: new multi-part Send API

    zmq4: add multi-part Send API
    
    benchstat between Send and SendMulti:
    name               old time/op  new time/op  delta
    PubSubSendMulti-8   26.9s ± 0%    7.2s ± 0%   ~     (p=1.000 n=1+1)

Release v0.6.2

all: fixup Go module for forked version of zeromq/goczmq

Fixes go-zeromq/zmq4#48.

Release v0.6.0

zmq4: add Addr method to Socket interface

Extend the zmq4.Socket interface with an `Addr() net.Addr` method.
This can be useful for service discovery.

Release v0.5.0

all: migrate to gopkg.in/zeromq/goczmq.v4

Release v0.4.0

zmq4: make sure PUB sockets do not block on SEND

Fixes #33.

Release v0.3.0

zmq4: add DOI badge

Release v0.2.0

internal/inproc: detect short-buffer during reads