Reordering the boot for fun and profit

I think the Debian approach is to hide the archaic concept of runlevels and avoid this
0,6,1,2,3,4,5 confusion altogether.

There are facilities for shutting down, rebooting, booting in rescue mode, and [re]starting
the GUI. Joe User doesn't need to be introduced to this wacky concept of runlevels.

(But he does need to know which display manager is the right one.)