Changed KeyframeBBox to TrackedObjectBBox and added TrackedObjectBase

Added new base class TrackedObjectBase, changed class KeyframeBBox to TrackedObjectBBox and changes it's inheritance from KeyframeBase to TrackedObjectBase.

src/TrackedObjectBase.cpp

@@ -0,0 +1,46 @@
+/**
+ * @file
+ * @brief Source file for the TrackedObjectBase class
+ * @author Jonathan Thomas <jonathan@openshot.org>
+ *
+ * @ref License
+ */
+
+/* LICENSE
+ *
+ * Copyright (c) 2008-2019 OpenShot Studios, LLC
+ * <http://www.openshotstudios.com/>. This file is part of
+ * OpenShot Library (libopenshot), an open-source project dedicated to
+ * delivering high quality video editing and animation solutions to the
+ * world. For more information visit <http://www.openshot.org/>.
+ *
+ * OpenShot Library (libopenshot) is free software: you can redistribute it
+ * and/or modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * OpenShot Library (libopenshot) is distributed in the hope that it will be
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "TrackedObjectBase.h"
+#include <algorithm>
+#include <functional>
+#include <utility>
+
+
+namespace openshot{
+
+    TrackedObjectBase::TrackedObjectBase(){
+		id = "None";
+    }
+
+	TrackedObjectBase::TrackedObjectBase(std::string _id){
+		Id(_id);
+	}
+}