SuReal: changed get-mapping

Expanded upon https://github.com/opencog/opencog/pull/1088 to allow UnorderedLink (by generating all possible permutation of the stuff in the UnorderedLink), and enforce structure match of hypergraph.

ie.  the whole structure of two atoms must match (taking care of unordered-links), and in that matched structure, one of the node's name must match
for a sub-type of unordered link why would a permutation be relevant?