Release: v2.0.0

- Use named pipes instead of signals to send requests to the daemon
- Each login session has its own named pipe tied to the PID of the
  login process, so daemons and schedulers in other sessions won't
  conflict with one another
- Introduce the reserved "daem" namespace for native daemon commands

TODO: Enable the scheduler to be able to signal daemons in all login
sessions. This is useful for global updates, like if you change the
volume and want the change reflected on all status bars.