Moved the MonadFoo classes to Control.Monad.Foo.Class.
  
  Put the instances consistently in the module which defines the type they
  give an instance for.
  
  Made the existing transformers lazy to match the existing monads, and put
  them in Control.Monad.Foo.Lazy. Also added Control.Monad.Foo.Strict with
  strict monads and transformers. Control.Monad.Foo still exports what it
  used to.
  
  Created a MonadRWS class.
  
  Made the MonadWriter w (ErrorT e m) instance strict to match everything
  else.