Fix User Interface
Reported Bug was:
When editing existing namespaces from second or later pagination, sometimes the ok button was disabled and never was enabled.
I could reproduce this by first edit the second last regular namespace, click on cancel, then edit the last regular namespace (regular means not talk NS).
This change destroys the NamespaceDialog on ok and on cancel, so the NamespaceDialog for the next namespace starts with new data.
closeAction:'destroy' had not the desired effect. Deeper reason unknown, but bug has gone.
Needs Cherrypick to REL1_31