Start to rework composition of trees

src/Dodge/Room/Start.hs

@@ -5,7 +5,7 @@ import Dodge.PlacementSpot
 import Dodge.Room.RunPast
 import Dodge.Data
 import Dodge.Default
-import Dodge.Layout.Tree.Either
+import Dodge.Tree
 import Dodge.RandomHelp
 import Dodge.Room.Door
 import Dodge.Room.Corridor
@@ -15,7 +15,6 @@ import Dodge.Room.Procedural
 import Dodge.Room.Foreground
 import Dodge.Room.RoadBlock
 import Dodge.Placement.Instance
-import Dodge.Layout.Tree.Polymorphic
 import Dodge.Item.Random
 import Dodge.Item.Weapon.BulletGuns
 import Dodge.Item.Weapon.Utility