1. Client: add "NAK avoidance."  We track our (and others, via snooping) block
   requests and avoid making re-requests unless it has been "long enough."

2. Server: more aggressive merging of requests in the work queue.  For every
   new request, look for any overlap with an existing entry.

3. Server: from Leigh: first cut at dynamic rate adjustment.  Can be enabled
   with -D option.

4. Both: change a lot of the magic constants into runtime variables so that
   they can be adjusted on the command line or via the event interface (see
   below).

5. Add code to do basic validatation of incoming packets.

6. Client: randomization of block request order is now optional.

7. Client: startup delay is optional and specified via a parameter N which
   says "randomly delay between 0 and N seconds before attempting to join."

8. Both: add a new LEAVE message which reports back all the client stats to
   the server (which logs them).

9. Both: attempt to comment some of the ...