OSMF SVN

Remove (undocumented) setupOverriddenTraits method. A ProxyElement subclass should set up its own traits by overriding setupTraits instead. If the subclass needs to access the proxiedElement during its trait setup operation, then it should override the proxiedElement setter to gain access to it and do that logic there. Updated plugins (captioning, MAST) and examples in ExamplePlayer to demonstrate this. Note that with this fix, overridden traits apply for the lifetime of the ProxyElement, rather than for the lifetime of the proxiedElement, which ought to be more intuitive.