Initial rewrite of the session handling code following the design
document. Deleted everything not ported, supported, or deprecated.
There's a bit more work left to do:
- Intelligently handling registration, so that we can disable the timer
  and let servers wait for all their connected clients to get on board
- Ability to allow clients to connect, register, leave, and then come
  back later
- Perhaps rewrite the RoundStateMachine and call it the
  DistributedStateMachine or something and make the Session code use it
  as well
- Stop is poorly handled
- There's nothing to handle disconnections or cause a restart of the
  protocol due to new connections
- Need more checks on packets properly formed
- Bring back deleted rounds namely CSBulk, BlogDrop, and NeffShuffle

[ClientServer] Rebuilt the Overlay module of Dissent, it no longer has
all to all messaging, that requires more work on the forwarders, but
this is sufficient for our anytrust protocols...