Adding `@context` information

The main functional change is the possibility to add @context information to the terms.

Numerous small additional updates and bugs, see CHANGES.md for details.

v1.4.5: Merge pull request #17 from w3c/wrong-ns-for-Property

Generation bug: Property was put into a wrong namespace.

Added datatypes, deprecation, context generations...

Main new features since previous release

• Optional generation of JSON-LD @context files for the vocabulary
• Properties can be explicitly defined as graph containers in JSON-LD (to be used when @context is generated)
• Comments in HTML
• Cross-references for domains and ranges between properties and classes
• Introduction of deprecated properties, and a status flag for reserved, deprecated, or stable
• Adding the possibility to define datatypes

See the CHANGES.md file for further details

Initial release

First formal release