Confidence property and default confidence values #263
Description
According to globalwordnet/schemas#79 and globalwordnet/schemas#89, the confidence value of lexicon elements defaults to the value on the <Lexicon> element, which defaults to 1.0 if not given. Wn currently does not implement this logic.
In order to do so, I think we should have a confidence accessor method or property that gets the default values, and leave obj.metadata().get("confidence") to be the actual value encoded in the data.
Lexicon extensions should have their own confidence value such that the default value for elements contributed by the extension is the confidence of the lexicon extension and not the base lexicon.