Implements some necessary code for the scrapper

Implements ignored salvage
Implements salvage-able items
Adds some TODOs
Implements salvage fail chance
Moves several methods to ItemHelper
Adds option for allowing extended salvage

src/main/java/net/knarcraft/blacksmith/trait/CustomTrait.java

@@ -186,6 +186,8 @@ public abstract class CustomTrait<K extends Setting> extends Trait {
             Objects.requireNonNull(((LivingEntity) npc.getEntity()).getEquipment()).setItemInMainHand(heldItem);
         }
         //Remove the item from the player's inventory
+        // TODO: For a scrapper with extended salvaging enabled, the item needs to be reduced with the amount specified
+        //  in the recipe, or removed as normal in the case where the player has exactly enough items to run the salvage. 
         player.getInventory().setItemInMainHand(null);
     }