5.3 Merge window, part 1

The amount of effort required for more ipv4 as we are doing it is trivial. It's a string of essentially one line patches to a dozen OSes, and a recompile of userspace, if you want to use the new formerly reserved for future multicast addresses. 89 packages, total, in fedora, needed to be recompiled (none, for 0/8, or 240/4)

And testing of course! We reached the point in our testbeds where nothing less than a global scale (e.g. a commit to linux mainline) test would prove anything.

Eventual politics and standardization efforts will eat 1000s more of (hopefully someone else's) time than either of these two phases.

IPv6 is way harder in many, many respects. And still, desperately needed.

Making 0/8 work, universally, is going to be *easy*.

Maybe if 0/8 creates enough controversy, someone will listen to me about what more is needed to accelerate ipv6 adoption.