Windows support

[Elizafox]

There's no good reason this shouldn't work on Windows, but I don't think it's worth the trouble. I'd have to refactor a few things that are Unix-specific.

If there's any demand, post it here.

What would be needed

• should be a proper service on Windows, not a daemon (different main() probably needed)
• PID file code should be no-op or not used on Windows
• non-syslog logger for Windows (not sure what else to use? does Windows have a logging framework?)
• signal-catching code would have to be refactored for Windows, but shouldn't be too hard
• privilege-dropping code may not be necessary on Windows and probably doesn't have to be ported; I don't know the policy regarding privileged ports