About to rewrite the way in which properties are handled in DataHives:
  1. Implicit: agent=thread=graph
  2. RDF: <dho:Agent,dho:creation,xsd:dateTime>
  3. Measurements: measure(Agent,dho:age)

* [DH_AGENT_PROPERTY,DOC] Started a separate documentation file.
* [DH_AGENT_PROPERTY,NEW] Added agent_self/1, graph_self/1.