Allow to set IPv4 and IPv6 explicitly in one query to update both A and AAAA record at once

[jkrenzer]

Hi!

My router is only able to issue one GET-query with placeholders for the IPv4 and IPv6 address to update a dDNS provider.

So I wanted to propose adding query-parameters to trigger updates of both the A and AAAA record from one query. From a quick look it seems this would need some additional mechanics in the UpdateIp function. I'd propose adding the type-explicite parameters myipv4 and myipv6 while keeping myip with automatic type determination around for backwards compatibility.

Cheers,

Jörn