StateT bug fix + monadic conditionals

• Fixed: a bug in the StateT monad-transformer. One of the SelectMany overloads wasn't propagating the state correctly.
• Changed: Prelude.local that creates a local IO and resource environment renamed to localIO to avoid conflicts with ReaderT.local and Reader.local
• Added: general purpose liftIO in Prelude
• Added: variants of when and unless that take a K<M, bool> as the source of the flag. Means any monad that binds a bool can be used directly in when and unless, rather than having to lower it first.
• Added: new monadic conditional: iff - works like when and unless, but has an else case. K<M, bool> can be used directly also, meaning that if/then/else monadic expressions can be built without lowering.
• Added: applicative actions to the Prelude. Allows for chaining n applicative actions, discarding their results, apart from the last one, which is returned