Someone

Owl - Facade
  - getListenerService : IListenerService (or IEventService) (contains add/remove/notify methods per model)
  - getConnectionService : IConnectionService
  - getInterpreter : IInterpreter
  - getModelFactory : IModelTypesFactory
  - getInterpreterFactory : IInterpreterTypesFactory (note Bug about merging the two factories)
  - getDefaultScope / getGlobalScope / getEntityScope => convinient methods for scoped preferences (not sure if we want an extra interface here?)
  
  - getPersistenceService : IPersistenceService (was PersistenceLayer)
    o getModelDAO
    o getPreferencesDAO
    o getApplicationLayer : IApplicationLayer
    o getModelSearch : IModelSearch
    o getIDGenerator : IDGenerator
        
Questions:

1.) Should we get rid of IPersistenceService (PersistenceLayer). All the elements inside that layer
seem to be contributable via separate extension points. That would mean flatten the getter of persistence-layer
into the facade of course.

2.) The DAO Bug has an impact on the API here of course. We could discuss this separately though and move the
old API over first.

3.) Better naming of IApplicationLayer?