Add default destination setting for traceng + some checks.

gns3server/controller/project.py

@@ -921,12 +921,7 @@ class Project:
         Start all nodes
         """
         pool = Pool(concurrency=3)
-        emit_warning = True
         for node in self.nodes.values():
-            if node.node_type == "traceng" and emit_warning:
-                self.controller.notification.emit("log.warning", {"message": "TraceNG nodes must be started one by one"})
-                emit_warning = False
-                continue
             pool.append(node.start)
         yield from pool.join()