isolate the oversized slots and itemhandlers

src/main/java/appeng/container/slot/SlotOversized.java

@@ -0,0 +1,9 @@
+package appeng.container.slot;
+
+import net.minecraftforge.items.IItemHandler;
+
+public class SlotOversized extends SlotNormal {
+    public SlotOversized(IItemHandler inv, int slot, int xPos, int yPos) {
+        super(inv, slot, xPos, yPos);
+    }
+}