Use new eslint-plugin-functional instead of tslint-immutable

src/file/header.ts

@@ -2,13 +2,17 @@ import { Paragraph } from "./paragraph";
 import { Table } from "./table";
 
 export interface IHeaderOptions {
-    readonly children: (Paragraph | Table)[];
+    readonly children: readonly (Paragraph | Table)[];
 }
 
 export class Header {
-    public constructor(public readonly options: IHeaderOptions = { children: [] }) {}
+    public constructor(public readonly options: IHeaderOptions = { children: [] }) {
+        // noop
+    }
 }
 
 export class Footer {
-    public constructor(public readonly options: IHeaderOptions = { children: [] }) {}
+    public constructor(public readonly options: IHeaderOptions = { children: [] }) {
+        // noop
+    }
 }