Called when open/close a project. Cleanup internal stuff

def reset(self):
        """
        Called when open/close a project. Cleanup internal stuff
        """
        self._allocated_node_names = set()
        self._nodes = {}
        self._links = {}
        self._drawings = {}
        self._snapshots = {}

        # List the available snapshots
        snapshot_dir = os.path.join(self.path, "snapshots")
        if os.path.exists(snapshot_dir):
            for snap in os.listdir(snapshot_dir):
                if snap.endswith(".gns3project"):
                    snapshot = Snapshot(self, filename=snap)
                    self._snapshots[snapshot.id] = snapshot

        # Create the project on demand on the compute node
        self._project_created_on_compute = set()