Client: fix disappearing node inventories on older servers

ee9258ce introduced a logic error, which caused clients to lose
node metadata when they should not and vice-versa.
See also: server.cpp / Server::sendAddNode

src/network/clientpackethandler.cpp

@@ -241,10 +241,10 @@ void Client::handleCommand_AddNode(NetworkPacket* pkt)
 	MapNode n;
 	n.deSerialize(ptr, m_server_ser_ver);
 
-	bool remove_metadata;
-	*pkt >> remove_metadata;
+	bool keep_metadata;
+	*pkt >> keep_metadata;
 
-	addNode(p, n, remove_metadata);
+	addNode(p, n, !keep_metadata);
 }
 
 void Client::handleCommand_NodemetaChanged(NetworkPacket *pkt)