I think we should finally fix the logging and release 1.0.

The problem is we currently don't log all the info we want (e.g. privmsgs, see #56). I think a logger function with type fn(&Conn, &ConnEv) would be really helpful to implement all of the logging logic in one place. Should not be too hard.

In the future I want to be able to show logs in the UI (e.g. when a privmsg tab is created with a user previous messages would be shown in the tab), but that's a lot of work and needs some more detailed design. Current design has the advantage that the log files are readable plain-text files.