Add literals, node, or predicate to the HAVING clause about badwolf HOT 2 CLOSED

The final orientation for this Issue was:

We shall not allow inequalities for nodes and predicates inside HAVING clauses, only equalities are allowed there for them (for clarity and to avoid confusion with regards to what is indeed being compared - the ID or the type of a node (or both)? the ID or the timestamp of a predicate? and so on). In the case of inequalities an error should be returned instructing the user to use the ID/TYPE/AT keywords and leverage the extracted bindings to do these comparisons in a clearer way.

For literals, on the other hand, we support both equalities and inequalities inside HAVING.

To illustrate, taking the example of predicate inequalities inside HAVING clauses, the user shall be oriented to do something like:

SELECT ?s, ?p, ?o
FROM ?family
WHERE {
    ?s ?p ID ?pID AT ?time ?o
}
HAVING (?pID < "parent_of"^^type:text) AND (?time > 2016-03-01T00:00:00-08:00);

But, if the user wants to do just an equality they can do it directly (as it does not cause any confusion):

SELECT ?s, ?p, ?o
FROM ?family
WHERE {
    ?s ?p ?o
}
HAVING ?p = "parent_of"@[];

The same applies for nodes.

from badwolf.

This Issue was finished with the PRs: #117, #134, #137, #138.

Previous work done on this Issue (mainly regarding node and literal comparisons): #102, #100.

from badwolf.