Add ability to use a provided ipv4 address on connect

Hi,

This patch pulls the fix in NameUtil as well as a shortcut to use a provided IPv4 address on connect. I'm not yet sure if I should also use an IPv6 address, it's at least provided.

IP addresses are randomized before use. DNS should do the same, but there are known exceptions.

This shortcut won't work if your SRV record points to a CNAME. But this is not recommended anyway and it won't break.

The only breakage would be if the client has IPv6 connectivity only. I'm not sure if this is an issue right now...