Add IntMapHelper, locate wall cutting bug

src/Dodge/LevelGen/Block.hs

@@ -7,13 +7,13 @@ import Dodge.WorldEvent.Sound
 import Dodge.LevelGen.Pathing
 import Geometry
 import Picture.Data
+import qualified IntMapHelp as IM
 
 import Control.Lens
 import Control.Monad.State
 import Data.List
 import Data.Maybe
 import Data.Function
-import qualified Data.IntMap.Strict as IM
 import System.Random
 
 updateBlocks :: World -> World
@@ -103,7 +103,7 @@ addBlock (p:ps) hp col isSeeThrough degradability w
         & walls     %~ IM.union panes
   where 
     lns = zip (p:ps) (ps ++ [p])
-    i = newKey $ _walls w
+    i = IM.newKey $ _walls w
     is = [i.. i + length lns-1]
     panes = IM.fromList $ zip is $ zipWith 
         (\j (a,b) -> Block