More control over interfaces supported by QAxServer

QAxServer allows the implementation of additional COM interfaces though QAxBindable/Aggregated, but it is not possible to remove interfaces from the implementation.

Implementing IPersistsPropertyBag will make some COM clients (i.e. PowerPoint) never use the IPersistStorage implementation, which makes it impossible to use certain data-storage features. Overriding the existing IPersistsPropertyBag in QAxAggregated (always return E_NOTIMPL) is not legal according to http://msdn2.microsoft.com/en-us/library/aa768206.aspx.