Multiple unit stance support

core/src/mindustry/ai/ItemUnitStance.java

@@ -8,17 +8,26 @@ import mindustry.type.*;
 
 public class ItemUnitStance extends UnitStance{
     private static ObjectMap<Item, ItemUnitStance> itemToStance = new ObjectMap<>();
+    private static Seq<ItemUnitStance> all = new Seq<>();
 
     public final Item item;
 
     public ItemUnitStance(Item item){
         super("item-" + item.name, "item-" + item.name, null);
         this.item = item;
+
+        incompatibleStances.add(UnitStance.mineAuto).addAll(UnitStance.mineAuto.incompatibleStances);
+
         itemToStance.put(item, this);
+        all.add(this);
     }
 
     public static @Nullable ItemUnitStance getByItem(Item item){
-        return itemToStance.get(item);
+        return item == null ? null : itemToStance.get(item);
+    }
+
+    public static Seq<ItemUnitStance> all(){
+        return all;
     }
 
     @Override