Added Opus stream support, added volume interface (#1102)

* Added opus stream support, added volume interface

* Remove setImmediate

* Fix weird syntax error

* Most useless commit ever

You're welcome, @PgBiel

* Fix potential memory leak with OpusScript

Emscripten has the tendency to not free resources even when the Opus engine instance has been garbage collected. Thanks to @abalabahaha for pointing this out.

* Typo

* VoiceReceiver.destroy: destroy opus encoder

src/client/voice/opus/BaseOpusEngine.js

@@ -10,6 +10,10 @@ class BaseOpus {
   decode(buffer) {
     return buffer;
   }
+
+  destroy() {
+    return;
+  }
 }
 
 module.exports = BaseOpus;