Makefile, distorted.lisp, hosts.lisp: Finish renumbering for A&A switchover.

  * Abolish the Hurricane Electric IPv6 range now that we have native
    IPv6.  I'm not going to try to do multihoming here.  Therefore, the
    A&A range takes over all of the house internal networks as well as
    the border.

  * Rearrange how the gateway addresses work.  It turns out that I have
    to allocate a little gateway network for the PPP terminating router:
    otherwise, it uses the wrong default source address for the PPP
    interface.