InvUtil and SpecialInv changes

Remove last places that instantiate InventoryUtil/InventoryUtilFactory directly.
Add IInventoryUtil interface
InventoryUtilFactory now returns IInventoryUtil instances
Convert SpecialInventory handlers to IInventoryUtil
Remove ISpecialInventoryHandler; SpecialInventoryHandler is now a abstract class handlers extend
Move SpecialInventory registration into InvUtilFactory
Add InventoryHelper with fixed buildcraft getInventory/transactor to fix derpiness with doublechest halves ordering.