Merge of r4993, r4994, r4997, r5000: geo ipv6 support. *) Geo: IPv6 support. The "ranges" mode is still limited to IPv4 only. *) Geo: properly initialize ngx_cidr_t when dealing with "default". *) Geo: made "default" affect both IPv4 and IPv6 when using prefixes. Previously, "default" was equivalent to specifying 0.0.0.0/0, now it's equivalent to specifying both 0.0.0.0/0 and ::/0 (if support for IPv6 is enabled) with the same value. *) Geo: improved code readability.