Fix reading of sections and pages

Elements read as classes were overwritten by the plain objects passed to 
the constructors.

projects/common/models/page.ts

@@ -2,7 +2,6 @@ import { Section } from 'common/models/section';
 
 export class Page {
   [index: string]: any;
-
   sections: Section[] = [];
   hasMaxWidth: boolean = false;
   maxWidth: number = 900;
@@ -13,7 +12,7 @@ export class Page {
   alwaysVisibleAspectRatio: number = 50;
 
   constructor(page?: Page) {
-    this.sections = page?.sections.map(section => new Section(section)) || [new Section()];
     Object.assign(this, page);
+    this.sections = page?.sections.map(section => new Section(section)) || [new Section()];
   }
 }

projects/common/models/section.ts

-import { PositionedUIElement } from 'common/models/elements/element';
+import { PositionedUIElement, UIElement } from 'common/models/elements/element';
 import { ElementFactory } from 'common/util/element.factory';
 
 export class Section {
@@ -15,13 +15,17 @@ export class Section {
   activeAfterID: string | null = null;
 
   constructor(section?: Partial<Section>) {
+    Object.assign(this, section);
     this.elements =
       section?.elements?.map(element => ElementFactory.createElement(element.type, element) as PositionedUIElement) ||
       [];
-    Object.assign(this, section);
   }
 
   setProperty(property: string, value: any): void {
     this[property] = value;
   }
+
+  getElements(): UIElement[] {
+    return this.elements;
+  }
 }