Make sure the ActionListEditor combo box has only useful collections
Make sure the ActionListEditor combo box has only useful collections

We got a flattened tree in the ActionListEditor combo box, no need to
keep all the intermediate collections around or the collections we
can't write to anyway. That's why we added a small internal filter
proxy which removes anything irrelevant preventing mistakes.

kolab-groupware/zanshin,kolab-groupware/zanshin,sandsmark/zanshin,sandsmark/zanshin,kolab-groupware/zanshin,sandsmark/zanshin