Merge pull request #176 from w3c/topic/parameterized-return-type-io

This is good enough. I think it will help Antonio to make his changes.
[util] Moved TryInstances into main rdf module.
[jena] Fix long line in JenaSolutionsWriter.
Merge pull request #179 from pellucidanalytics/topic/parameterized-return-type-io

parameterized return type io -- small fixes