proper support for Windows/Cygwin: "zipperposition" vs. "zipperposition.exe";
chapter Tools
session Tools = Pure +
  theories
    Code_Generator
session Spec_Check in Spec_Check = Pure +
  theories
    Spec_Check
    Examples
session SML in SML = Pure +
  theories
    Examples
session Haskell in Haskell = Pure +
  theories
    Haskell
  theories [condition = ISABELLE_GHC_STACK]
    Test