Resolve "Support and documentation for default-strict lists"

Closes #237 (closed).

These features were added in Clean 3.1 (see mailing list: [clean-list] Clean 3.1 available for Windows, Linux and Mac OS X).

I was unsure where to add the new derive/instance feature, that would be a sensible follow-up:

- derive a member of an instance using a generic function with
  the same type, for example

  instance == T where
    derive == gEq

  derives an == member of type T using generic function gEq.

  If there is only one member, this can also be written as:

  instance == T derive gEq

  The default member of a class can also be derived, for example:

  class equal a where
    equal :: a a -> Bool
    derive equal gEq

  instance equal T