Wraps the internal inventory into an ItemListIgnoreCrafting to hide
craftable items from it. As the ItemLists will always create a copy of the
actual stack before changing them, it will not affect any itemstack stored
elsewhere.
(cherry picked from commit a9c5019554)
Reduces the visibility of all fields to private and create setters/getters
when necessary. Exceptions are fields with GuiSync as these need to be
public.
Reduces the visibility of internal methods to private/protected/default when possible.