Fixed i3bar id, now starting from 0.
Made i3exit.bash multiscreen-aware.
Added output for volume and for eth0.

Note that the output of volume needs the kernel module snd-pcm-oss to be
loaded.

    echo "snd-pcm-oss" >> /etc/modules-load.d/snd-pcm-oss.conf
Restructured ~/.i3/config.