CZMQ version 4.0.2 stable, released on 2016/12/31
- Fixed #1559 - DRAFT zsock_new_*_checked symbols leak
- Fixed #1560 - zsock options could be available at build time but
not at runtime. Added runtime check, an error will
be printed if the option is not available.
- Fixed #1565 - improved compatibility with Solaris/Illumos
- Fixed #1573 - memory leak when message send fails in internal usage