Permission component

[maparent]

We have permission arrays in many levels:
member, quest_membership, guild_membership, casting, role, role_node_constraint.
We want to edit these in many places in the admin UX. It would make sense to create a generic permission component; presumably based on multi selection widget.
it would receive as props:

1. an object of which it only knows that it has an (optional) permission array.
2. list of preferences that can be set on this object (we could subset to only permission that it makes sense to define at this level
3. list of permission that have been set at a higher level in the hierarchy, and hence do not need to be set and cannot be unset locally.

It would probably send a signal to its owner component whenever a permission is added/removed; the owning component would know the object type and could call the appropriate update function.