Add ItemStackRef class and supporting elements to PC[Tile]EntityRef
Add ItemStackRef class and supporting elements to PC[Tile]EntityRef

EntityRefs now try to know their blockTypes. This mainly allows 1.7 worlds to return an item's internalName for its ID when accessed. With the caveat that an item created outside of a world and assigned a 1.7 ID will return a 1.7 ID until it is parented to a world. I can live with that.

Rubisk/mcedit2,vorburger/mcedit2,Rubisk/mcedit2,vorburger/mcedit2