Added support for prodinfo in the plugin and ontology... but it needs some refining #43
\<prodinfo> is skipped if prodname doesn't contain text() (that means only static value os valid, nnot a dynamically resolved) close #43
removed keyref preprocessing step #57
Fixed prodinfo invalid RDF close #43, improved reference following and support for conref close #33, opens the way for #57
Merged ditaot-plugin