Refactor shell movement, modularised in a tweakable way

src/Dodge/Item/Weapon/Targeting.hs

@@ -0,0 +1,20 @@
+module Dodge.Item.Weapon.Targeting
+    where
+import Dodge.Data
+
+import Control.Lens
+import qualified Data.IntMap.Strict as IM
+useTargetPos 
+    :: (Maybe Point2 -> Creature -> World -> World)
+    -> Creature
+    -> World
+    -> World
+useTargetPos f cr w = case cr ^? crInv . ix (_crInvSel cr) . itTargeting . _Just of
+    Nothing -> w
+    Just (g,_) -> f (g w) cr w
+
+removeItTarget :: Int -> Int -> World -> World
+removeItTarget i _ w = w & creatures . ix i . crInv . ix itRef . itTargeting .~ Nothing
+  where 
+    cr = _creatures w IM.! i
+    itRef = _crInvSel cr