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.

java/org/artisanlogiciel/games/minetest/Node.java

@@ -3,6 +3,7 @@ package org.artisanlogiciel.games.minetest;
 import java.util.HashMap;
 
 public class Node {
+    // could be a core.v3s16
     int x;
     int y;
     int z;