add support for floating drawings

- added need elements and test for them

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

@@ -0,0 +1,17 @@
+import { assert } from "chai";
+
+import { SimplePos } from "./simple-pos";
+import { Utility } from "../../../tests/utility";
+
+describe("SimplePos", () => {
+    describe("#constructor()", () => {
+        it("should create a element with correct root key", () => {
+            const newJson = Utility.jsonify(new SimplePos());
+            assert.equal(newJson.rootKey, "wp:simplePos");
+            assert.include(newJson.root[0].root, {
+                x: 0,
+                y: 0,
+            });
+        });
+    });
+});