----------------
- Pass `**kwargs` to DocumentGenerationView._render_document so it is possible to pass
arbitrary parameters to appy.pod.renderer.Renderer that is called in _render_document
and to which we also pass the `**kwargs`.
This way, it is possible for example to turn `Renderer.raiseOnError` to True.
[gbastien]
- Added meta_type for content_types `PODTemplate`, `ConfigurablePODTemplate`, `SubTemplate`
and `StyleTemplate`, this way it can be used to filter out objectValues/objectIds.
[gbastien]
- Added a validator on the configurablePODTemplates which check if the chosen generations
formats are corrects with the kind of file provided.
[boulch, DieKatze]