New features:
- Write a proper user's manual.
- Implement playlist looping (repeating the current playlist indefinitely).
- Implement skipping to the next playlist in a list.
- Write a GUI client.
- Make moosicd save state upon exit.
- The moosic client should automatically start up the server if it's not already
  running, cleaning up after a previously crashed server if necessary.
- Eliminate the output from externally spawned processes in a manner that always
  works.

Implementation details:
- Use stream-oriented sockets instead of datagram-oriented sockets in order to
  remove the ugly necessity for the client to create and listen to its own
  separate socket just to get data back from the server.
- This change in the IPC will require a better formalization of the
  communication protocol between the client and the server, particularly in
  regard to handshaking.
- Wrap the functionality of the moosic client into a library to ease the
  development of alternative client programs.

Maybe-list:
- Write a Web frontend to the moosic client.
- Make moosicd act like a real Unix daemon (detaching from the console, logging
  to syslog, all that jazz).
