read a .we minetest schema

- use ground has maze walls

java/org/artisanlogiciel/games/minetest/Range.java

@@ -0,0 +1,71 @@
+package org.artisanlogiciel.games.minetest;
+
+public class Range {
+    int min;
+    int max;
+
+    public int getMin() {
+        return min;
+    }
+
+    public int getMax() {
+        return max;
+    }
+
+    public Range()
+    {
+        // invalid range, means empty interval
+        min = 0;
+        max = -1;
+    }
+
+    public boolean isEmpty()
+    {
+        return ( min > max );
+    }
+
+    boolean union(Range other)
+    {
+        boolean update = false;
+        if ( ! other.isEmpty()) {
+            update = updateBounds(other.getMin()) | updateBounds(other.getMax());
+        }
+        return update;
+    }
+
+    boolean updateBounds(int v)
+    {
+        boolean update = false;
+
+        // special case where previous range was unset ( min > max ).
+        if ( isEmpty() )
+        {
+            min = v;
+            max = v;
+            return true;
+        }
+        if ( v < min )
+        {
+            update = true;
+            min = v;
+        }
+        if ( v > max )
+        {
+            update = true;
+            max = v;
+        }
+        return update;
+    }
+
+
+    public int getRangeSize() {
+        if (isEmpty())
+        {
+            return 0;
+        }
+        else
+        {
+            return max - min;
+        }
+    }
+}