bracket

What do you think about adding a mimicking of the `bracket` function of `Exception`?
It ensures that the `release` action is performed before any errors of the `apply` are raised.

``` haskell
bracket ::
(Monad m) =>
EitherT e m a ->
(a -> EitherT e m b) ->
(a -> EitherT e m c) ->
EitherT e m c
bracket acquire release apply = do
r <- acquire
z <- lift $ runEitherT $ apply r
release r
hoistEither z
```