postfix: don't do mail routing

This is not its job. Let the main Postfix server do that.
x11: configure keyboard and mouse from xorg.conf

This is quite cumbersome but we need this to support hotplug. Other
solutions doesn't handle a keyboard that is plugged after
configuration (or they require Gnome). The drawback is that we need to
modify a system file and we need to restart X for changes to take
effects...
x11: copy evdev rules file to avoid accidental suppression

When upgrading the system, the file will be copied back to its previous
content. Avoid that by using a self-updating copy.