Added ONMjs.Address.visitChildAddresses method...

... When working on ONMjs.Address yesterday I found it interesting to notice which observers I was breaking when I moved methods and properties of ONMjs.Address to ONMjs.Address.implementation. In most cases I was able to fix the observer by re-writing the observer implementation code in terms of higher-level ONMjs API methods (which is the goal). This commit adds ONMjs.Address.visitChildAddresses and fixes the last of the observers from yesterday that still had a hard dependency on ONMjs.Address.implementation. With this commit, I should now be able to refactor ONMjs.Address to hide all of its detail in ONMjs.Address.implementation and not break any observer.