Use dedicated XmlComponent rather than polute pure one

src/file/xml-components/initializable-xml-component.ts

@@ -0,0 +1,11 @@
+import { XmlComponent } from "file/xml-components";
+
+export abstract class InitializableXmlComponent extends XmlComponent {
+    constructor(rootKey: string, initComponent?: InitializableXmlComponent) {
+        super(rootKey);
+
+        if (initComponent) {
+            this.root = initComponent.root;
+        }
+    }
+}