* Yang "min-element" and "max-element" feature supported

* New Clixon Yang RPC: ping. To check if backup is running.
* Fixed support for multiple datanodes in a choice/case statement.

yang/clixon/clixon-lib@2019-01-02.yang

@@ -52,4 +52,7 @@ module clixon-lib {
 	    }
 	}
     }
+    rpc ping {
+	description "Check aliveness of backend daemon.";
+    }
 }