implement most remaining BB team functions

src/Client.hh

@@ -54,7 +54,6 @@ struct Client : public std::enable_shared_from_this<Client> {
     HAS_EP3_MEDIA_UPDATES               = 0x0000000010000000,
     USE_OVERRIDE_RANDOM_SEED            = 0x0000000020000000,
     HAS_GUILD_CARD_NUMBER               = 0x0000000040000000,
-    ACCEPTED_TEAM_INVITATION            = 0x0000000080000000,
 
     // Cheat mode flags
     SWITCH_ASSIST_ENABLED               = 0x0000000100000000,
@@ -232,7 +231,7 @@ struct Client : public std::enable_shared_from_this<Client> {
   std::shared_ptr<ServerState> require_server_state() const;
   std::shared_ptr<Lobby> require_lobby() const;
 
-  std::shared_ptr<TeamIndex::Team> team();
+  std::shared_ptr<const TeamIndex::Team> team();
 
   static void dispatch_save_game_data(evutil_socket_t, short, void* ctx);
   void save_game_data();