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/ByteArrayTag.h

@@ -19,7 +19,8 @@ public:
 	void load(DataInput *dis)
 	{
 		int length = dis->readInt();
-		
+		if (length < 0 || length > 2 * 1024 * 1024) length = 0;
+
 		if ( data.data ) delete[] data.data;
 		data  = byteArray(length);
 		dis->readFully(data);