Intent to close ISSUE-207

I've updated the expansion algorithm to eliminate free-floating nodes
(values and IRIs; but not lists) as decided in ISSUE-207 [1]. This has the
nice side-effect that we can align the data model closer to RDF's - which
does not support free-floating nodes.

Unless I hear objections, I will proceed and close ISSUE-207 in 24 hours.


Cheers,
Markus


[1] https://github.com/json-ld/json-ld.org/issues/207


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Markus Lanthaler
@markuslanthaler