Store the original item ID after enchantment
During enchanting, if enchanted item name, original item ID and enchanting ID are the same, we may re-use existing enchanted item dynamic record instead of creating a new one. It would be useful for projectiles enchanting (to stack self-enchanted projectiles).
Unfortunately, we do not store an original item ID yet - we need to change a savegame format for it.
Also this feature would be useful later for Lua modmaking (e.g. to detect stolen/smuggled goods).