Switch to new event system (#9)

* `SignalEvents` and `synchronized` mode for `EventsListenable`

* cascade syntax

* clean up

* `RoomEvents`

* `ParticipantEvents`

* all events implemented

* make it compile with M1 macs

* dispose logic

* cleaner connect logic

* ask to publish

* fix initial EngineTrackAddedEvent glitch

* fix unpublishTrack bug

* clean up

* better events docs

* organize event types

* clean up

* cleaner wait logic

* wait for event instead of using Completer

* notifyListeners

pubspec.yaml

@@ -10,13 +10,23 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  flutter_webrtc: ^0.6.7
+  
   http: ^0.13.3
   logging: ^1.0.2
   uuid: ^3.0.4
   synchronized: ^3.0.0
   protobuf: ^2.0.0
 
+  flutter_webrtc: 
+    git:
+      url: https://github.com/livekit/flutter-webrtc
+      ref: use-custom-webrtc-build
+
+    # ^0.6.7
+    # path: ../../repos_livekit/flutter-webrtc/
+    # This will use custom webrtc build from
+    # https://github.com/webrtc-sdk/Specs/releases
+
   # protobuf:
   #   git:
   #     url: https://github.com/google/protobuf.dart.git