* Both a "native" stream support and one using nginx/nchan pub/sub.
* See (apps/restconf/README.md) for details.
* clixon-config YAML file has new revision: 2018-10-21.
* If you used old event callbacks API, you need to switch to the streams API
* See clixon_stream.[ch]
* Old streams API which needs to be removed include:
* clicon_log_register_callback()
* subscription_add() --> stream_register()
* backend_notify() and backend_notify_xml() - use stream_notify() instead
* Example uses "NETCONF" stream instead of "ROUTING"
* Added timeout option -t for clixon_netconf - quit after max time.