Reflect inheritance hierarchy in interfaces
Reflect inheritance hierarchy in interfaces

container.Base inherits from block.Element, so make IReadContainer inherit from
IElement to facilitate security declarations. zeit.content.cp declares security for its regions in terms of IReadContainer/IWriteContainer, I don't think it makes sense to force it to declare IElement in addition

ZeitOnline/zeit.edit,ZeitOnline/zeit.edit,ZeitOnline/zeit.edit