fix: add splitscreen, fix dlcs not loading, major RCE vuln fix on packet net, fix chunk loading on non-server clients, persistent saves

note: I changed how XUID works, player data might be wiped on old saves, save items on a chest or similar before trying to load old saves on new version

Minecraft.World/ContainerSetContentPacket.cpp

@@ -32,6 +32,9 @@ void ContainerSetContentPacket::read(DataInputStream *dis) //throws IOException
 {
 	containerId = dis->readByte();
 	int count = dis->readShort();
+
+	if(count < 0 || count > 256) count = 0;
+	
 	items = ItemInstanceArray(count);
 	for (int i = 0; i < count; i++) 
 	{