ticket is associated with a different PSK. This provides somewhat
increased security in cases where you have multiple PSKs for the
same connection and one PSK is compromised.

The motivation here is that in cases where the server maintains a
session database rather than self-encrypted tickets, the server might
delete tickets as they are used,. This change provides FS for
connections which have been used, even if there are other outstanding
tickets in the session cache associated with the same original
connection.

Colm MacCarthaigh. Specifically:

- Describe both one time tickets and client hello storage
  ("strike register") mechanisms and SHOULD-level require
  people to do them.

- Provide a security considerations section describing the
  threats.