Item constructor id sentinel (for metadata items)

Add a sentinel for Item constructor which will prevent item from been registered into Item.itemsList, but still create an instance of an Item. It will be very helpful in creating metadata based items. Like:

[spoiler=Item constructor]public Item(int par1)

    {

        this.itemID = 256 + par1;

        if (this.itemID < 0 || this.itemID >= itemsList.length) return;

        if (itemsList[256 + par1] != null)

        {

            System.out.println("CONFLICT @ " + par1 + " item slot already occupied by " + itemsList[256 + par1] + " while adding " + this);

        }

        itemsList[256 + par1] = this;

        GameData.newItemAdded(this);

    }

[spoiler=MetaItem example]public class MetaItem extends Item

{

    // int metadata ->Item item

    public Set<Integer,Item> metaItems = new HashSet<Integer,Item>();

    public MetaItem(int itemID)

    {

        super(itemID);

        setNoRepair();

        setMaxDamage(0);

        setHasSubTypes(true);

    }

    public void put(int metadata, Item item)

    {

        item.setNoRepair();

        item.setMaxDamage(0);

        item.setHasSubTypes(true);

        metaItems.put(metadata, item);

    }

    // do hooks to desired functions, like this:

    @Override

    @SideOnly(Side.CLIENT)

    public void registerIcons(IconRegister iconRegister)

    {

        for (Item i : metaItems.values())

        {

            i.icon = iconRegister.registerIcon(i.iconName);

        }

    }

    @Override

    public Icon getIconFromDamage(int metadata)

    {

        Item i = metaItems.get(metadata);

        return (i != null) ? i.icon : null;

    }

    // ...

}

[spoiler=MetaItem usage example]

public static final int METAID = -257

MetaItem mi = new MetaItem(metaItemID);

mi.metaItems.put(0, new ItemGeneric(METAID, ...));

mi.metaItems.put(20, new ItemFood(METAID, ...)); // own subclass from ItemFood

mi.metaItems.put(40, new ItemArmor(METAID, ...)); // own subclass from ItemArmor, possibly will work only for non damageable armor, e.g. damage handling need to be moved to nbt by mod developer

mi.metaItems.put(60, new ItemTool(METAID, ...)); // own subclass from ItemTool, possibly will work only for non damageable tools, e.g. damage handling need to be moved to nbt by mod developer

mi.metaItems.put(100, new ItemDust(METAID, ...));

mi.metaItems.put(200, new ItemIngot(METAID , ...));

mi.metaItems.put(300, new ItemPlate(METAID, ...));