ONMjs v0.0.12 Refactor ONMjs.Namespace implementation into subnamespace...

Okay... I think this is nearly the last of the refactorings I had been putting off. AFAIK, now all ONMjs public classes hide their details in an 'implementation' subnamespace. Take a dependency on that stuff at you're likely toast on the next library update. Everything above the implementation namespace is intended to be documented and used directly by developers.