Extend ReSpec to generate Terms sections for specification documents from a common vocabulary file

Currently each specification of the OSLC Core multi-part specifications has a Terms section that is generated by ReSpec from Turtle files that documents the vocabulary ontology for that section.

However, OSLC core has a single namespace, and therefore requires a single ontology resource for the whole vocabulary, and the ability to render that ontology as an HTML page.

The OSLC Core TC decided to use one vocabulary document and extend ReSpec to generate the Terms sections for each multi-part specification from a list of classes and properties that should be included in that section.

Specifically, for section with class="appendix", div section attribute data-include will refer to the complete OSLC Core vocabulary (vocab/core-vocab.ttl) and new property data-include-content will provide a list of classes and properties that should be included in the Terms section (based on the data-oninclude="vocabToSpec" value). ReSpec should then use these classes and properties to generate the vocabulary HTML content from the single core-vocab.ttl file.