add support for floating drawings

- added need elements and test for them

src/file/drawing/floating/simple-pos.ts

@@ -0,0 +1,28 @@
+// http://officeopenxml.com/drwPicFloating-position.php
+import { XmlComponent, XmlAttributeComponent } from "file/xml-components";
+
+interface ISimplePosAttributes {
+    x: number;
+    y: number;
+}
+
+class SimplePosAttributes extends XmlAttributeComponent<ISimplePosAttributes> {
+    protected xmlKeys = {
+        x: "x",
+        y: "y",
+    };
+}
+
+export class SimplePos extends XmlComponent {
+    constructor() {
+        super("wp:simplePos");
+
+        // NOTE: It's not fully supported in Microsoft Word, but this element is needed anyway
+        this.root.push(
+            new SimplePosAttributes({
+                x: 0,
+                y: 0,
+            }),
+        );
+    }
+}