encode/decode data-embed-code attribute (#374)

Author: linkesch

src/js/core.js

@@ -146,8 +146,9 @@
 
             // Restore original embed code from embed wrapper attribute value.
             $data.find('[data-embed-code]').each(function () {
-                var $this = $(this);
-                $this.html($this.attr('data-embed-code'));
+                var $this = $(this),
+                    html = $('<div />').html($this.attr('data-embed-code')).text();
+                $this.html(html);
             });
 
             data[key].value = $data.html();

src/js/embeds.js

@@ -429,7 +429,7 @@
                 // Store embed code with <script> tag inside wrapper attribute value.
                 // Make nice attribute value escaping using jQuery.
                 $div = $('<div>')
-                    .attr('data-embed-code', html)
+                    .attr('data-embed-code', $('<div />').text(html).html())
                     .html(html);
                 html = $('<div>').append($div).html();
             }