refactor(audio): completely remove Audio class dependency from Core

The Audio singleton instance initializes itself on startup. No need for an extra call.

src/core/core.cpp

@@ -25,7 +25,6 @@
 #include "src/core/coreav.h"
 #include "src/persistence/settings.h"
 #include "src/widget/gui.h"
-#include "src/audio/audio.h"
 #include "src/persistence/profilelocker.h"
 #include "src/net/avatarbroadcaster.h"
 #include "src/persistence/profile.h"
@@ -64,9 +63,6 @@ Core::Core(QThread *CoreThread, Profile& profile) :
 {
     coreThread = CoreThread;
 
-    Audio::getInstance();
-
-
     toxTimer = new QTimer(this);
     toxTimer->setSingleShot(true);
     connect(toxTimer, &QTimer::timeout, this, &Core::process);