More Accesible Quad Module

[constraintAutomaton]

Description

This branch makes Scryer's quad-based testing easier to discover and easier to use programmatically.

• The quadtests, testutils, and special_functions modules move out of src/lib/numerics/ and into a new src/lib/testing/ directory. I think they are not really numerics specific and the module name offuscate a bit the purpose of quads.

• evaluated_quads/2 predicate created. This predicate return an term evaluation(passed(Passed), rejected(Rejected)) and does not have a side effect of printing in the top level, to enable better reasoning over the quad answer.

• Documentation added for the module and in the README.md.

related to #3303 and #3301

[constraintAutomaton]

I will make the example more interesting and demonstrative of Scryer Prolog capability.

[constraintAutomaton]

@UWN Do you think those examples and the new interface is representative of the intended usage of quads?

[triska]

But why? The error can be directly used as answer description:

?- functor(X, F, A).
   error(instantiation_error,functor/3).

[constraintAutomaton]

It seems like it is not currently supported.

If I do this

:- module(foo, [foo/1]).

foo(a) :- throw(custom_error(bar)).
foo(b).

?- foo(b).
  true.
?- foo(a).
  throw(custom_error(bar)).

and in my top-level

check_module_quads(foo, X).

I get this

 false.

if I remove the quad then I get a valid answer,

[constraintAutomaton]

If it is indeed a bug/unexpected behavior and not a mistake from my part, I can fix it with this PR. Given you think it is in scope for this PR.