Implement simple swarm mechanics

src/Dodge/Creature/State/Data.hs

@@ -9,7 +9,7 @@ import Dodge.Creature.Stance.Data
 import Picture.Data
 
 import Control.Lens
-import qualified Data.Set as S
+import qualified Data.IntSet as IS
 
 data CreatureState = CrSt 
     { _goals    :: [[Impulse]]
@@ -42,7 +42,7 @@ data Faction
 
 data CrGroup
     = LoneWolf
-    | Swarm { _swarm :: S.Set Int }
+    | Swarm { _swarm :: IS.IntSet }
 
 makeLenses ''CreatureState
 makeLenses ''CrSpState