closednamespace inheritance fix on 5.0.0-dev

[joernhees]

the fix for #542 in #551 was backwards incompatible and thus not fit for the patch release 4.2.2 and reverted in #595

this issue is a reminder to either replay bccc761 and ae1f639 on top of 5.0.0-dev or maybe drop the unicode base-class for Namespace altogether...

@gromgull any preference?

[gromgull]

I would drop unicode for namespace, I cannot really see any use-cases why it is useful that it's a subclass at all?

Then let ClosedNamespace inherit from Namespace

[niklasl]

👍 Totally agree.

[joernhees]

please have a look at #597

[kernc]

I cannot really see any use-cases why it is useful that it's a subclass at all?

How does one filter for "properties" from DCTERMS namespace if not by:

for p, o in g.predicate_objects(s):
    if p.startswith(DCTERMS):
        ...