TODO
====

- when negative AppendResponse rec'd, send next one immediately
    - simpler logic: always xmit if different from previous message

- separate Loggers for:
    - transactions
    - messages (recv & xmit)
    - raft logic

- more memory-efficient Writes class

- fix issue where TCP connections are established in both directions ?

- apply more than one log entry at a time in a single atomic write if appropriate

