webrtc-try

First trying webrtc

The second fight with webrtc (has an ally 'peerjs' this time). (First fight was webrtc-try). Steps for use:

1. If you want to run signaling server locally, run the signaling server by npm start
2. Open index.html (also open again on different tab or window for other user)
3. Type localhost, 9000, peerjs into signaling server address or leave blank to use peerjs's hosted signaling server. (see https://peerjs.com/peerserver.html and https://peerjs.com/docs.html#peer-options-config)
4. Enter your username and remote username (who you want to connect)
5. Press to "Connect to server"
6. Select your devices
7. Press call (no need on other side)