Merge pull request #2416 from adumesny/master

disableOneColumnMode: true for web demo

Author: adumesny

demo/web1.html

@@ -25,6 +25,7 @@ <h1>Web demo 1</h1>
   <script type="text/javascript">
     let grid = GridStack.init({
       cellHeight: 70,
+      disableOneColumnMode: true,
     });
 
     let items = [

demo/web2.html

@@ -62,6 +62,7 @@ <h1>Advanced Demo</h1>
       cellHeight: 70,
       acceptWidgets: true,
       removable: '#trash', // drag-out delete class
+      disableOneColumnMode: true,
     });
     GridStack.setupDragIn('.newWidget', { appendTo: 'body', helper: 'clone' });