IPv6 Support

[samuong]

The PAC "standard" as defined by Netscape includes a few functions that assume IPv4, so Alpaca currently only supports IPv4.

Microsoft has a few extensions which work better for IPv6 and Google has implemented some of these functions into Chrome (although they make these functions available in the regular FindProxyForURL function, rather than just scoping it to FindProxyForURLEx). These include dnsResolveEx() and myIpAddressEx(), and they both replace functions that return IPv4 addresses only with functions that could return either (or both).

There are also other functions that accept IPv4 addresses, and should be extended to accept IPv6 addresses as well. These include isResolvable() and isInNet().

The only remaining function is convert_addr(). There doesn't appear to be an IPv6 version in Mozilla, Microsoft or Google's implementations, and it doesn't make sense for Alpaca to implement its own extension to the standard, so I'll leave this as it is.