Make creature update an external function

src/Dodge/Payload.hs

@@ -0,0 +1,9 @@
+module Dodge.Payload where
+import Geometry.Data
+import Dodge.Data
+import Dodge.WorldEvent.Explosion
+
+usePayload :: Payload -> Point2 -> World -> World
+usePayload payload = case payload of
+    ExplosionPayload -> makeExplosionAt
+    DudPayload -> const id