Have an "accesses/share"-pane for administering users
A plan (on the review-system) currently has two types of users:
- viewers
- editors
Being an editor implies also being a viewer.
There's no easy way to convert between the two. All changes to user-access to a plan need to be collected in one place. That is:
- invitations, and everything connected to that
- changing the status of an existing user, including removing that user. But who gets to remove users?
- user should be able to lower or remove their own access to a plan, so that an editor can change themself into a viewer instead, or leave the plan altogether.