Sprite-authored support for the community fixtures.

Files:
  Test/Prop.curry

This compile-only interface is used by Sprite, not by the PAKCS oracle.
It supplies the property signatures needed by the unchanged source programs.
Every operation raises if evaluated; the second batch added the signatures
of is, solutionOf and (<=>) after the first batch's, so the operation indices
of the first batch's products are unchanged. The Goals adapters evaluate the original
expressions instead of pretending to execute a CurryCheck property.
