Scala continuations

WIP

https://www.scala-lang.org/files/archive/api/2.11.12/scala-continuations-library/#scala.util.continuations.package

• A @cpsParam[-B, +C] corresponds to (a -> m b) -> m c in Haskell. The shift and reset operations in the Scala docs correspond to the ones in the Haskell docs modulo the Haksell ones not being indexed, and some extra lifts or returns being inserted or eliminated.