Embedding monad transformers in carrier stacks is fiddly about fused-effects HOT 2 CLOSED

I think this can be addressed by two additions to the lib:

1. MonadTrans instances for all the relevant carriers. Almost all of these are pretty trivial, or at least will be once #114 is in.

2. A generic Carrier wrapper for MonadTrans instances, e.g.:

   newtype TransC t (m :: * -> *) a = TransC { runTransC :: t m a }
     deriving (Applicative, Functor, Monad, MonadIO, MonadTrans)
   
   instance (Carrier sig m, Effect sig, Monad (t m), MonadTrans t) => Carrier sig (TransC t m) where
     eff = TransC . join . lift . eff . handle (pure ()) (pure . (runTransC =<<))

from fused-effects.

I think MonadTrans instances will suffice for 0.3; TransC can be defined by users of the lib, whereas (non-orphan) MonadTrans instances cannot.

from fused-effects.