a few warnings removed from rio
Add rdf:langString from RDF 1.1  to OWL/RDF vocabulary.

Make BUILT_IN_ANNOTATION_PROPERTY_IRIS unmodifiable

Add Nonnull annotations.
cleanup warnings from contract
cleanup warnings from oboformat
cleanup warnings from tools
cleanup warnings from api test
cleanup warnings from impl
clenaup warnings from impl test
cleanup warnings from api
Switch comments to correct types
cleaned FindBugs warnings
Merge pull request #178 from sesuncedu/add_rdf_langString_to_vocab

Add rdf:langString from RDF 1.1  to OWL/RDF vocabulary.
refactored HasIRI to IRI as a function

This can be used in a smorgasbord of places. More to come.