Jerry Tao

#### Description When using ORTC API, the new accepted channel don't set the sctpTransport, see https://github.com/pion/webrtc/blob/master/sctptransport.go#L219. it will panic if someone try to use it: ``` pair, err := channel.Transport().Transport().ICETransport().GetSelectedCandidatePair()...

#### Description When creating IceGather in ortc allow use custom ufrag and pwd.

Remove the pending buffer after the data channel call close() by either side.

2

## Summary Remove the pending buffer after the channel is closed by either side. ## Motivation Please refer to #238 ## Describe alternatives you've considered In the official WebRTC code,...

Expose extension fields

10

#### Description The Extension in the RTP header is exposed, but the id and payload are not. I think it would make sense for these two fields to also be...