Use strict-containers for IntMaps

src/Dodge/Floor.hs

@@ -35,7 +35,7 @@ import RandomHelp
 import Data.List (intersperse)
 --import Data.Sequence hiding (zipWith)
 --import Data.Maybe
---import qualified Data.IntMap.Strict as IM
+--import qualified IntMapHelp as IM
 
 initialAnoTree :: Annotation
 initialAnoTree = OnwardList