MaimMim Man in the middle minetest interceptor

- prototype
- between client and server, allow to capture all exchanges and potentially change them
- created to capture server maps in laby
- first test get only MapBlock, support version serialization version 28
  - prepartion for 29 with zstd but untested.

# Conflicts:
#	fetch_dependencies.sh

java/org/artisanlogiciel/games/minetest/net/BufferedPacket.java

@@ -0,0 +1,28 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+import org.artisanlogiciel.games.minetest.core.Serialize;
+
+public class BufferedPacket {
+
+    public static int BASE_HEADER_SIZE = 7;
+
+    // Data of the packet, including headers
+    byte[] m_data;
+
+    BufferedPacket(byte[] data)
+    {
+        m_data = data;
+    }
+
+    int getSeqNum()
+            throws PacketException
+    {
+        return Serialize.readU16(m_data, BASE_HEADER_SIZE + 1, size());
+    }
+
+    int size()
+    {
+        return m_data.length;
+    }
+}