Improve the "my own URLs" construction, such that:
- IPv6 link-local addresses are always skipped. They require a "zone index"
string, typically the interface name, so something like
`[fe80::cafe:f00d%eth0]`. This is not supported by web browsers, so the
URLs would be of limited use. Furthermore, they require the interface
name of the side initiating the connection, whereas this code is used to
answer the question "how can this machine be reached as a server?"
- IPv4 addresses are sorted before IPv6 addresses. Even though I like IPv6
a lot, IPv4 is still more familiar to people.
- Loopback addresses (::1, 127.0.0.1) are sorted last, so that the First-
Time Wizard is most likely to use the bigger-scoped address.
