Refactors CustomItemStack to not extend ItemStack

[md5sha256]

Refactors CustomItemStack to no longer extend ItemStack. All CIS constructors are now replaced with .create() methods with identical arguments. Additionally an ItemStackEditor fluent class with helper methods to edit the ItemMeta on an ItemStack is the builder equivalent.
Example:

ItemStack item = new CustomItemStack(...);

With

ItemStack item = CustomItemStack.create(...);

or

ItemStack item = new ItemStackEditor(material).setX(...).setX(...).create();