Actually re-broadcast host change

Took 8 minutes

libcockatrice_protocol/libcockatrice/protocol/pb/serverinfo_game.proto

@@ -62,4 +62,7 @@ message ServerInfo_Game {
 
     // whether the game is closed. Closed games are finished and can't be interacted with
     optional bool closed = 52;
+
+    // the current host of the game, which may differ from the creator after a host transfer
+    optional ServerInfo_User host_info = 53;
 }