Better policy support for IPv6

Better policy support for IPv6

Now, "accept *:80" means "accept all addresses on port 80", and not
just IPv4.  For just v4, say "accept *4:80"; for just v6 say "accept
*6:80".

We can parse these policies from torrc just fine, and we should be
successfully keeping them out of descriptors for now.

We also now include appropriate IPv6 addresses in "reject private:*"