Add IntMapHelper, locate wall cutting bug

src/Dodge/WorldEvent/SpawnParticle.hs

@@ -19,9 +19,9 @@ import Dodge.RandomHelp
 import Dodge.Debug
 import Picture
 import Geometry
+import qualified IntMapHelp as IM
 
 import Control.Lens
-import qualified Data.IntMap.Strict as IM
 import System.Random
 import Control.Monad.State
 import Data.Function (on)
@@ -228,7 +228,7 @@ makeGasCloud pos vel w = w
     & clouds    %~ IM.insert i theCloud
     & randGen   .~ g
   where 
-    i = newKey $ _clouds w
+    i = IM.newKey $ _clouds w
     theCloud = Cloud { _clID = i
                      , _clPos = pos
                      , _clVel = vel