Sound IsReady Function

Check If Sound Is Ready (Use full to check before calling sound.play
AND for sounds that are serialized and have NO CHANCE to assign
‘ReadySoundCallback’ in constructor from being parsed from scene file)

src/Audio/babylon.sound.ts

@@ -227,6 +227,10 @@ module BABYLON {
             }
         }
 
+        public isReady(): boolean {
+            return this._isReadyToPlay;
+        }
+
         private _soundLoaded(audioData: ArrayBuffer) {
             this._isLoaded = true;
             Engine.audioEngine.audioContext.decodeAudioData(audioData, (buffer) => {