RTCPeerConnection & Jingle

This module extends the RTCPeerConnection API to emit and process data in a JSON
format instead of SDP.

To use it, create your RTCPeerConnection with
``
const pc = new RTCPeerConnection({sdpSemantics: 'json'});
`

The createOffer and createAnswer methods will add a JSON field to the
RTCSessionDescription while the setRemoteDescription` method processes
this field and transforms it to SDP.

The transformation is done using the sdp module and reensembles
the data structures used by the ORTC-WebRTC shim.
This format can easily be transformed to the Jingle format used by jxt,
allowing the use of Jingle for signaling.

This package superceedes the older RTCPeerConnection package. Wrapping the native RTCPeerConnection API in a nice wrapper was necessary in 2013 but is no longer required these days.