Rework AEItemStack (#3091)

* Use itemstack as itemdef
* HIGH_TAG/LOW_TAG should be compared both directions
* Remove getTagCompound
* Make Itemlist implementation independent
* Cache item id for performance reasons
* Add preconditions to saveguard against external meddling
* Chache itemDamage
* Remove IAEStackSearchKey for now, rename getDisplayStack

src/main/java/appeng/tile/inventory/AppEngInternalInventory.java

@@ -122,7 +122,7 @@ public class AppEngInternalInventory extends ItemStackHandler implements IIntern
 			ItemStack oldStack = this.previousStack;
 			InvOperation op = InvOperation.SET;
 
-			if( newStack.isEmpty() || oldStack.isEmpty() || Platform.itemComparisons().isEqualItem( newStack, oldStack ) )
+			if( newStack.isEmpty() || oldStack.isEmpty() || ItemStack.areItemsEqual( newStack, oldStack ) )
 			{
 				if( newStack.getCount() > oldStack.getCount() )
 				{