Remove mtl dependency

src/RandomHelp.hs

@@ -2,12 +2,14 @@
 {- Helpers for random generation.  -}
 module RandomHelp (
     module System.Random,
-    module Control.Monad.State,
+--    module Control.Monad.State,
     module RandomHelp,
+    module Control.Monad.Trans.State.Lazy,
 ) where
 
 import Control.Monad
-import Control.Monad.State
+--import Control.Monad.State
+import Control.Monad.Trans.State.Lazy
 import Data.List
 import Geometry
 import StrictHelp