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/NetworkPacket.java

@@ -0,0 +1,70 @@
+package org.artisanlogiciel.games.minetest.net;
+
+import org.artisanlogiciel.games.minetest.core.PacketException;
+import org.artisanlogiciel.games.minetest.core.Serialize;
+import org.artisanlogiciel.games.minetest.core.v3s16;
+
+import java.nio.ByteBuffer;
+
+public class NetworkPacket {
+
+    int m_protocol_id;
+    int m_peer_id;
+    int m_channel;
+    public PacketType packetType;
+
+    // somehow a BufferedPacket ...
+    byte[] m_buffer; // m_data
+    // used part in buffer
+    int m_length; // m_datasize ?
+    // current header index in packet
+    int m_offset; // m_read_offset
+
+    short m_command = 0;
+
+    public NetworkPacket(int protocol_id, int peer_id, int channel, PacketType type, byte[] buffer, int length) {
+        this.m_protocol_id = protocol_id;
+        this.m_peer_id = peer_id;
+        this.m_channel = channel;
+        this.packetType = type;
+        m_buffer = buffer;
+        m_length = length;
+        m_offset = 0;
+    }
+
+    public int getChannel()
+    {
+        return m_channel;
+    }
+
+    public byte[] getBuffer()
+    {
+        return m_buffer;
+    }
+
+    public int getOffset() {
+        return m_offset;
+    }
+
+    public int getLength() {
+        return m_length;
+    }
+
+    void addOffset(int offset)
+    {
+        m_offset += offset;
+    }
+
+    // Serialization
+    public v3s16 v3s16()
+            throws PacketException
+    {
+        return Serialize.readV3S16(m_buffer, m_offset, m_length);
+    }
+
+    public ByteBuffer getByteBuffer()
+    {
+        ByteBuffer buffer = ByteBuffer.wrap(m_buffer,m_offset,m_length-m_offset);
+        return buffer;
+    }
+}