Add PDF Shortcut (#672)

* Add Blogtrottr as newsletter provider

* Fixed absLangURL issue with sections in footer

* Added embed-pdf shortcode

pdf-js is sered locally to preserve privacy and comply with GDPR

Co-authored-by: Emruz Hossain <hossainemruz@gmail.com>

static/js/pdf-js/web/images/secondaryToolbarButton-documentProperties.svg

@@ -0,0 +1,15 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16
+16">
+<path 
+   d="M8 16a8 8 0 1 1 8-8 8.009 8.009 0 0 1-8 8zM8 2a6 6 0 1 0 6 6 6.006 6.006 0 0 0-6-6z">
+</path>
+<path 
+   d="M8 7a1 1 0 0 0-1 1v3a1 1 0 0 0 2 0V8a1 1 0 0 0-1-1z">
+</path>
+<circle
+   cx="8" cy="5" r="1.188">
+</circle>
+</svg>