ListItem improvements

        ListItem         A list item, e.g. a step in a checklist or how-to description.         Subclass of: StructuredValue

        itemPosition         The position of the item in an ordered list (1 = first, 2 = second, ...).         Domain: ListItem         Range: Number

item The entity represented by the entry in the list (e.g. the artist, song, ...). Domain: ListItem Range: Thing

previous A link to the ListItem that preceeds the current one. Domain: ListItem Domain: ListItem

next A link to the ListItem that follows the current one. Domain: ListItem Domain: ListItem