This patch needs to be backported based on the outcome of #364734.

#345711 by Amitaibu. Let modules alter Og grants before written to the DB. makes it easier to support multiple node access modules along with custom business logic.

#345857. 'My groups' at path og/my show raw code ... Also switched one hook_form_alter branch to use the form_id specific variant.

* Updated German translation files.

#334256 by moshe weitzman and danielnolde. don't let group admins delete their group node. if you want this behavior, you can get very close by granting the permission to 'delete own [group content type]' to authenticated user role.