IPv6 support

[ksuprynowicz]

Just an initial commit, currently it's broken.
Please mark andy related TODOs as:
// TODO(IPv6):
so that they are easier to find.

[ksuprynowicz]

Currently Interface fails to connect to regular domain servers with this error:

[11/10 15:00:15] [CRITICAL] [hifi.networking] PAGE: Failed to lookup address of STUN server stun1.l.google.com
[11/10 15:00:15] [WARNING] [hifi.networking] PAGE: Failed to lookup public address via STUN server at stun1.l.google.com:19302 (likely a critical error for auto-networking).
[11/10 15:00:15] [DEBUG] [hifi.networking] LimitedNodeList public socket will be set with local port and null QHostAddress.
[11/10 15:00:15] [WARNING] [hifi.networking] Ignoring attempt to save current address with an invalid url: QUrl("")
[11/10 15:00:15] [DEBUG] [hifi.networking] Trying to go to URL "hifi://furry_avatars/-0.0238526,-0.568962,4.54922/0,0.8725,0,0.488613"
[11/10 15:00:15] [DEBUG] [hifi.networking] Possible domain change required to connect to "195.201.114.16" on 40202
[11/10 15:00:15] [DEBUG] [hifi.networking] Resetting current domain connection information.
[11/10 15:00:15] [DEBUG] [hifi.networking] Soft reset
[11/10 15:00:15] [DEBUG] [hifi.networking] Hard reset in NodeList DomainHandler.
[11/10 15:00:15] [DEBUG] [hifi.networking] Updated domain hostname to "195.201.114.16"
[11/10 15:00:15] [DEBUG] [hifi.networking] Looking up DS hostname 195.201.114.16.
[11/10 15:00:15] [DEBUG] [hifi.networking] DomainAccountManager domain URL has been changed to hifi://195.201.114.16:40202
[11/10 15:00:15] [DEBUG] [hifi.networking] Updated domain port to 40202
[11/10 15:00:15] [DEBUG] [hifi.networking] Failed domain server lookup
[11/10 15:00:15] [WARNING] [hifi.networking] Ignoring attempt to save current address because not connected to domain: QUrl("hifi://furry_avatars/-0.0238526,-0.578349,4.54922/0,0.8725,0,0.488613")

[ksuprynowicz]

When I try to connect by IP address it doesn't work and this happens:

[11/10 15:10:40] [DEBUG] [hifi.networking] Trying to go to URL "hifi://195.201.114.16:40202/-0.0238526,-1.10437,4.54922/0,-0.644783,0,0.764365"
[11/10 15:10:40] [DEBUG] [hifi.networking] Possible domain change required to connect to domain at "195.201.114.16" on 40202
[11/10 15:10:40] [DEBUG] [hifi.interface] MyAvatar goToLocation - moving to -0.0238526, -1.10437, 4.54922
[11/10 15:10:40] [DEBUG] [hifi.interface] MyAvatar goToLocation - new orientation is 0, -0.644783, 0, 0.764365
[11/10 15:10:40] [WARNING] [hifi.networking] Ignoring attempt to save current address because not connected to domain: QUrl("hifi://195.201.114.16:40202/-0.0238526,-1.10437,4.54922/0,-0.644783,0,0.764365")