New class ProjectAudioManager implements AudioIO callbacks

src/menus/TransportMenus.cpp

@@ -472,7 +472,7 @@ void OnTimerRecord(const CommandContext &context)
          // However, we can't undo it here because the PushState() is called in TrackPanel::OnTimer(),
          // which is blocked by this function.
          // so instead we mark a flag to undo it there.
-         ProjectManager::Get( project ).SetTimerRecordCancelled();
+         ProjectAudioManager::Get( project ).SetTimerRecordCancelled();
          break;
       case POST_TIMER_RECORD_NOTHING:
          // No action required