Still TODO before callout support is "complete":
1) Enhance handling of received file names
   a) On pkt or bundle files, place in sbbsecho inbound directory. with
      a known unique name... don't rely on the remote to make one up.
   b) For req files, handle the file request directly.
   c) All other files, place somewhere else for processing.
2) Perform actions when files are received... touch semaphores, parse TIC, etc.
3) Update flo files after a partial run... mark successful transfers as skip.
4) Put real data into the .try file.