[RFC PATCH 0/6] NAKs and PRODs

[Ian Jackson]

Currently, there are situations where secnet won't recover properly
after a restart of one of the ends.  In this series we (mostly) fix
this.

We also tidy up some of the documentation relating to NAKs.

 1/6 magic: Introduce LABEL_NAK
 2/6 site: Send NAKs for undecryptable data packets (msg0)
 3/6 NOTES: Improve documentation of NAKs.
 4/6 NOTES: Remove paragraph about slow-to-prepare messages
 5/6 site: Clearer processing for name-addressed packets
 6/6 site: New PROD message

NB that this series is an RFC.  It compiles but HAS NOT BEEN EXECUTED.