only return clients to newserv from proxy if not in a game

src/ProxyServer.hh

@@ -82,6 +82,7 @@ public:
     std::vector<LobbyPlayer> lobby_players;
     size_t lobby_client_id;
     size_t leader_client_id;
+    bool is_in_game;
 
     std::shared_ptr<PSOBBMultiKeyDetectorEncryption> detector_crypt;