Filtering by group

In the current translation overview list, there are dropdown filter boxes for filtering by content type, publishing status etc..

Esp. for sites with many nodes or for sites where translation is only required for some parts of the site, it would also be helpful to have a similar filter for filtering nodes by organic group affiliation. This would be meaningful for both the normal translation overview view (admin/content/translation-overview-manage) and the translator assignments view (admin/content/translation-overview-assignments).