Expose this error so pion/webrtc can handle gracefully.
rfc8839#section-5.1 specifies that a WebRTC Agent MUST
ignore any name/value pairs it doesn't understand.
Relates to pion/webrtc#1949
- Fix an issue with ipv6 srflx candidates gathering.
- Add SetNetworkTypes config to SettingEngine to control what network
types are allowed to be connected.
Resolves#460