more expansive supporting_studies attribute in subtree

[mtholder]

In the NodeNamerSupportedByStasher class' std::string operator()(const SumTreeNode_t *nd) const we are only adding things to the collection of supporting studies if they match the SUPPORTED_BY_MAPPING flavor: (see the if (el.first == SourceEdgeMappingType::SUPPORTED_BY_MAPPING) line).

It would be nice to return the Partial path of and perhaps terminal studies too.

It would be nice if it was obvious to API users how the supported by statements are showing up in the info panel of the browser (there I think they are more expansive than simply SUPPORTED_BY...)