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/OpusScriptEngine.js

@@ -2,7 +2,7 @@ const OpusEngine = require('./BaseOpusEngine');
 
 let OpusScript;
 
-class NodeOpusEngine extends OpusEngine {
+class OpusScriptEngine extends OpusEngine {
   constructor(player) {
     super(player);
     try {
@@ -22,6 +22,11 @@ class NodeOpusEngine extends OpusEngine {
     super.decode(buffer);
     return this.encoder.decode(buffer);
   }
+
+  destroy() {
+    super.destroy();
+    this.encoder.delete();
+  }
 }
 
-module.exports = NodeOpusEngine;
+module.exports = OpusScriptEngine;