• remove aspectManager getter
• registerAspectHelper to setRootEntity
• initialize and cleanup in ctor, dtor

• RenderSceneBuilder : hidden in QAbstractAspect
• Have a BackendCreatorFunctor that we use to register the creationCommand of
  a backend class from a frontend class
• Generate a TYPEID foreach frontend element

template<class Frontend>
registerBackendType(TYPEID, backendCreatorFunctor)