UNSTABLE: added block.break! which breaks a block

This almost feels like breaking the block with a pickaxe or
something. Their material will be randomly dropped on the Ground which
makes this a quite nice feature. However, in many cases (not yet
reproduced) the Client will die due to NullPointerException! So be
warened, this is higly unstable!

examples/generators/tunnel.rb

@@ -36,7 +36,7 @@ def on_enable
           block = deep_block.block_at(height_facing,height_dist)
           width.times do |width_dist|
             # for now the block will only be replaced by air. No mining.
-            block.block_at(width_facing,width_dist).change_type :air
+            block.block_at(width_facing,width_dist).break!
           end
         end
       end

src/bukkit/block/block.rb

@@ -58,6 +58,13 @@ def rotate(face,direction)
     face_for_symbol(ROTATIONS[symbol_for_face(face)][direction])
   end
 
+  def break!
+    mat = self.get_type
+    itemstack = org::bukkit::inventory::ItemStack.new(mat,1)
+    location.world.drop_item_naturally(location,itemstack)
+    self.change_type :air
+  end
+
   def face_for_symbol(value)
     FACE_VALUES[value]
   end