How to add OPItems:
    1. Define it in managers.items.cel20.opitems.RawItemsGenerator
    2. Add a recipe in allRecipes.items.cel20.opitems.RecipeAdder

How to make an item Functional:
    1. Get the id of the item being added
    2. Programm the functions
    3. Register Listeners in items.cel20.opitems.EventManager