minetest worledit .we format export

- harcoded generation of lua content of .we export
- export something, but not yet correct ( walls are points ... )

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

@@ -1,4 +1,31 @@
 package org.artisanlogiciel.games.minetest;
 
 public class Node {
+    int x;
+    int y;
+    int z;
+    String material;
+
+    public Node(int x, int y, int z, String material) {
+        this.x = x;
+        this.y = y;
+        this.z = z;
+        this.material = material;
+    }
+
+    public int getX() {
+        return x;
+    }
+
+    public int getY() {
+        return y;
+    }
+
+    public int getZ() {
+        return z;
+    }
+
+    public String getMaterial() {
+        return material;
+    }
 }