Comment 8 for bug 101103

Drat, this is going to be more work than I originally thought, and also require an upgrader.

Three methods: get_silva_addables_allowed_in_publication and is_silva_addables_acquired and set_silva_addables_allowed_in_publication, and _addables_allowed_in_publication all need to be moved to the Folder class.

I would recommend changing their names, replacing 'publication' with 'container'. This means the upgrader needs to:
1) change _addables_allowed_in_publication to end in '_container' for any IPublication (including the SilvaRoot and possible SilvaNewsPublications, perhaps others?)
2) add _addables_allowed_in_container to all other containers

I'll work in an upgrader for this.