added comments to PropertyCompleteness metric
removed useless method of SchemaCompletenessTest
added tests for PropertyCompleteness metric
added population completeness metric
minor cleanups in SchemaCompleteness class
fixed wrong mappings and created new dump

I mistakenly used

  ?dept = uri('http://ex.org/', ?id)

instead of

  ?dept = uri('http://ex.org/', ?dept)
minor cleanups in SchemaCompletenessTest class
added yet unimplemented dataset measure support to value test sink
minor cleanups in PropertyCompletenessTest class
added tests for population completeness metric