Introduce utility function for deriving table fields

tools/electric_hoe.lua

@@ -15,8 +15,7 @@
 -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 local S=minetest.get_translator("industrialtest")
-industrialtest.ElectricHoeBase=table.copy(industrialtest.ActivatedElectricTool)
-industrialtest.internal.unpackTableInto(industrialtest.ElectricHoeBase,{
+industrialtest.ElectricHoeBase=industrialtest.internal.derive(industrialtest.ActivatedElectricTool,{
 	digs={"hoey"},
 	capacity=10000,
 	flow=industrialtest.api.lvPowerFlow
@@ -130,8 +129,7 @@ function industrialtest.ElectricHoeBase.getOpPower(self,itemstack)
 	return 50
 end
 
-industrialtest.ElectricHoe=table.copy(industrialtest.ElectricHoeBase)
-industrialtest.internal.unpackTableInto(industrialtest.ElectricHoe,{
+industrialtest.ElectricHoe=industrialtest.internal.derive(industrialtest.ElectricHoeBase,{
 	name="industrialtest:electric_hoe",
 	description=S("Electric Hoe"),
 	inventoryImage="industrialtest_electric_hoe.png",
@@ -164,8 +162,7 @@ minetest.register_craft({
 })
 
 if industrialtest.mclAvailable then
-	industrialtest.AdvancedElectricHoe=table.copy(industrialtest.ElectricHoeBase)
-	industrialtest.internal.unpackTableInto(industrialtest.AdvancedElectricHoe,{
+	industrialtest.AdvancedElectricHoe=industrialtest.internal.derive(industrialtest.ElectricHoeBase,{
 		name="industrialtest:advanced_electric_hoe",
 		description=S("Advanced Electric Hoe"),
 		inventoryImage="industrialtest_advanced_electric_hoe.png",