[ACA-1608] lazy loading support for Viewer and About screens (#526)

* move viewer and directives to separate modules

* lazy loading for Viewer and About screens

* lazy loading support for extensions module

src/app/components/preview/preview.module.ts

@@ -0,0 +1,63 @@
+/*!
+ * @license
+ * Alfresco Example Content Application
+ *
+ * Copyright (C) 2005 - 2018 Alfresco Software Limited
+ *
+ * This file is part of the Alfresco Example Content Application.
+ * If the software was purchased under a paid Alfresco license, the terms of
+ * the paid license agreement will prevail.  Otherwise, the software is
+ * provided under the following open source license terms:
+ *
+ * The Alfresco Example Content Application is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * The Alfresco Example Content Application is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import { CoreModule } from '@alfresco/adf-core';
+import { CommonModule } from '@angular/common';
+import { NgModule } from '@angular/core';
+import { Routes, RouterModule } from '@angular/router';
+
+import { DirectivesModule } from '../../directives/directives.module';
+import { AppInfoDrawerModule } from '../info-drawer/info.drawer.module';
+import { PreviewComponent } from './preview.component';
+import { ContentDirectiveModule } from '@alfresco/adf-content-services';
+
+import * as pdfjsLib from 'pdfjs-dist';
+pdfjsLib.PDFJS.workerSrc = 'pdf.worker.js';
+pdfjsLib.PDFJS.disableFontFace = true;
+
+const routes: Routes = [
+    {
+        path: '',
+        component: PreviewComponent
+    }
+];
+
+@NgModule({
+    imports: [
+        CommonModule,
+        RouterModule.forChild(routes),
+        CoreModule.forChild(),
+        ContentDirectiveModule,
+        DirectivesModule,
+        AppInfoDrawerModule
+    ],
+    declarations: [
+        PreviewComponent,
+    ],
+    exports: [
+        PreviewComponent
+    ]
+})
+export class PreviewModule {}