define amendment.selection even if selection is deleted
define amendment.selection even if selection is deleted

Without this, entity_url on a deleted amendment will fail

As amendments always have one single selection and are
below that in the hierarchy I guess it is reasonable
to keep the selection around even if it is deleted.

phihag/adhocracy,DanielNeugebauer/adhocracy,alkadis/vcv,liqd/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,alkadis/vcv,liqd/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,phihag/adhocracy,DanielNeugebauer/adhocracy,phihag/adhocracy,alkadis/vcv,phihag/adhocracy,liqd/adhocracy,DanielNeugebauer/adhocracy,liqd/adhocracy,phihag/adhocracy