This patch uses the new internal bare-bones Inventory constructor and the new internal method Inventory.InitializeFromSkeleton to initialize the inventory with owner and root information after it has been constructed. This is so that we can have the InventoryStore and LibraryStore instances immediately ready when GridClient is instantiated. Note: InventoryStore.RootFolder will return null until after InventoryManager.OnSkeletonsReceived is fired, because we don't know anything about the inventory yet!