onpart (Irc::IrcBot)

    # File rbot/ircbot.rb, line 658
      def onpart(m)
        if(m.address?)
          log "@ Left channel #{m.channel} (#{m.message})", m.channel
          @channels.delete(m.channel)
          puts "left channel #{m.channel}"
        else
          log "@ #{m.sourcenick} left channel #{m.channel} (#{m.message})", m.channel
          @channels[m.channel].users.delete(m.sourcenick)
        end

        # delegate to plugins
        @plugins.delegate("listen", m)
        @plugins.delegate("part", m)
      end