Extracted API extensions introduced by features, such as the P2P Data API, from the PeerConnection API.
Removed bad section tag.
Merge branch 'idl-feature-split'

Conflicts:
	webrtc.html

Used the newer getStats() method from the main PeerConnection interface.
Updated DTMF algorithm to dispatch an event when insertDTMF() is called with an empty string to cancel future tones.