improve handling of dns resolution and ipv6 address when bound to an ipv4 socket

[bmwill]

A udp socket that is bound to an ipv4 address cannot trivially communicate with an ipv6 address. Despite this we should probably make a better effort when bound to an ipv4 address by:

• looking at all addresses from the dns resolution process and find a suitable address (instead of always grabbing the first)
• attempting to convert an ipv6 address to an ipv4 mapped address when possible.

[Itznur]

Well impressive