Optimize AxiomTranslator#containsONTObject(..) and #findONTObject(..) for the case of anonymous expression in main triple (Node.ANY)

[sszuev]

this is a continuation of #20

Several axioms, such as SubClassOf, usually have named subject and anonymous object.
There is a searching by predicate (i.e. $any rdfs:subClassOf $any + filter) and refined searching for the case of named triple (exact match with $some rdfs:subClassOf $some - issue #20) .

Need a general way to optimize the cases of $some $some $any and $any $some $some.

[sszuev]

The main cases are covered, all others are rare.
Optimizations for these rest cases can be proposed later, when an understanding of their need arises: right now the existing mechanisms seem to be good enough.