now extends XmlComponent

ts/docx/document/body/doc-grid.ts

@@ -1,15 +1,10 @@
 import {XmlComponent, Attributes} from "../../xml-components";
 
-export class DocumentGrid implements XmlComponent {
-    private docGrid: Array<XmlComponent>;
-    
-    xmlKeys = {
-        docGrid: 'w:docGrid'
-    }
+export class DocumentGrid extends XmlComponent {
 
     constructor() {
-        this.docGrid = new Array<XmlComponent>();
-        this.docGrid.push(new Attributes({
+        super("w:docGrid");
+        this.root.push(new Attributes({
             linePitch: "360"
         }));
     }