Implemented int getBlockTypeIdAt(int x, int y, int z).

src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -54,6 +54,10 @@ public class CraftWorld implements World {
         return block;
     }
 
+    public int getBlockTypeIdAt(int x, int y, int z) {
+        return world.a(x, y, z);
+    }
+
     public int getHighestBlockYAt(int x, int z) {
         return world.d(x, z);
     }