Better audio management (#10)

* add audio_session package

* `AudioManager` initial design

* try to integrate audio manager

* configure audio session

* `DisposeAware`

disposing if already published causes exception.

* organize

* guard flutter_webrtc calls

* websocket async fix

* use `ConnectionState` instead of `_isClosed` and `isReconnecting`

* change create audio track defaults

* update protos

* protocol 3 speaker updates

* fix exception

* emit `RoomDisconnectedEvent` only once

* fix exception

* keep track of local / remote audio tracks

* explicit types

* manage track state

* re-structure audio management

* change defaults

* unpublish all

* use experimental build

* change defaults

* configuring is optional

* call native `RTCAudioSession.setConfiguration`

* defaults adjustment

* iOS only for now

* use lib 92.4515.07

* clean up

* revert audio options for now

* remove pod source

* rename apple related audio

* `createListener` method

* organize native audio

* `SpeakingChangedEvent` only on `Participant`

* refactoring

* fix ios compile

* fix configure audio only for iOS logic

* minor fix & clean up

* change dispose logic

* format protos

* fix unpublishTrack

* `createListener` into a mixin

* simplify

* use flutter_webrtc master

* unpublish for example

* update ios icon

* android icon

* web icon

* favicon

ios/.gitignore

@@ -0,0 +1,38 @@
+.idea/
+.vagrant/
+.sconsign.dblite
+.svn/
+
+.DS_Store
+*.swp
+profile
+
+DerivedData/
+build/
+GeneratedPluginRegistrant.h
+GeneratedPluginRegistrant.m
+
+.generated/
+
+*.pbxuser
+*.mode1v3
+*.mode2v3
+*.perspectivev3
+
+!default.pbxuser
+!default.mode1v3
+!default.mode2v3
+!default.perspectivev3
+
+xcuserdata
+
+*.moved-aside
+
+*.pyc
+*sync/
+Icon?
+.tags*
+
+/Flutter/Generated.xcconfig
+/Flutter/ephemeral/
+/Flutter/flutter_export_environment.sh