consume resume token during VerifyToken
consume resume token during VerifyToken

Independently of this, ClientLookupSet.Resume ensures that at most one
resume can succeed, so this doesn't actually change the behavior.
But ResumeManager should be a standalone example of how to implement
resume without race conditions.

oragono/oragono,DanielOaks/oragono,oragono/oragono,oragono/oragono,DanielOaks/oragono