Thread a more complex structure through the placement process

src/Dodge/LevelGen/LevelStructure.hs

@@ -7,9 +7,12 @@ import Dodge.Data
 
 --import Data.Tree
 import qualified Data.IntMap.Strict as IM
+import Control.Lens
 --import System.Random
 
 data GenWorld = GenWorld
     { _gWorld       :: World
     , _gPlacements  :: IM.IntMap [Placement]
     }
+worldToGenWorld w = GenWorld w IM.empty
+makeLenses ''GenWorld