add double confirmations for delete actions
I think it would be good to ask users to double confirm specific delete actions:
- deleting a group: if is wasn't really intended all content that is shared with the group is not available for the members anymore
- deleting a timeline: can contain a lot of videos and annotations, everything is gone
- deleting a video: can contain a lot of annotations (they are not gone, but can be really difficult to resync)
- deleting a grid: a bit similar, a lot work can potentially be destroyed