add support for floating drawings

- added need elements and test for them

src/file/drawing/anchor/anchor-attributes.ts

@@ -0,0 +1,26 @@
+import { XmlAttributeComponent } from "file/xml-components";
+import { Distance } from "../drawing";
+
+export interface IAnchorAttributes extends Distance {
+    allowOverlap?: "0" | "1";
+    behindDoc?: "0" | "1";
+    layoutInCell?: "0" | "1";
+    locked?: "0" | "1";
+    relativeHeight?: number;
+    simplePos?: "0" | "1";
+}
+
+export class AnchorAttributes extends XmlAttributeComponent<IAnchorAttributes> {
+    protected xmlKeys = {
+        distT: "distT",
+        distB: "distB",
+        distL: "distL",
+        distR: "distR",
+        allowOverlap: "allowOverlap",
+        behindDoc: "behindDoc",
+        layoutInCell: "layoutInCell",
+        locked: "locked",
+        relativeHeight: "relativeHeight",
+        simplePos: "simplePos",
+    };
+}