fix(metadata): allow whitespaces after closing marks

Co-authored-by: Estevão Soares dos Santos <estevao.santos@gmail.com>

src/subParsers/makehtml/metadata.js

@@ -34,12 +34,12 @@ showdown.subParser('makehtml.metadata', function (text, options, globals) {
     });
   }
 
-  text = text.replace(/^\s*«««+(\S*?)\n([\s\S]+?)\n»»»+\n/, function (wholematch, format, content) {
+  text = text.replace(/^\s*«««+\s*(\S*?)\n([\s\S]+?)\n»»»+\s*\n/, function (wholematch, format, content) {
     parseMetadataContents(content);
     return '¨M';
   });
 
-  text = text.replace(/^\s*---+(\S*?)\n([\s\S]+?)\n---+\n/, function (wholematch, format, content) {
+  text = text.replace(/^\s*---+\s*(\S*?)\n([\s\S]+?)\n---+\s*\n/, function (wholematch, format, content) {
     if (format) {
       globals.metadata.format = format;
     }

test/functional/makehtml/cases/features/#709.allow-whitespaces-after-end-in-metadata.html

@@ -0,0 +1,8 @@
+<p><strong>some</strong> markdown text</p>
+<ul>
+    <li>a list</li>
+    <li>another list ---</li>
+    <li>and stuff</li>
+</ul>
+<p>a paragraph --- with dashes</p>
+<hr />

test/functional/makehtml/cases/features/#709.allow-whitespaces-after-end-in-metadata.md

@@ -0,0 +1,16 @@
+---         
+
+title: This is the document title
+language: en
+author: Tivie
+
+---       
+**some** markdown text
+
+- a list
+- another list ---
+- and stuff
+
+a paragraph --- with dashes
+
+---

test/functional/makehtml/testsuite.features.js

@@ -100,6 +100,8 @@ describe('makeHtml() features testsuite', function () {
         converter = new showdown.Converter({openLinksInNewWindow: true});
       } else if (testsuite[i].name === '#355.simplifiedAutoLink-URLs-inside-parenthesis-followed-by-another-character-are-not-parsed-correctly') {
         converter = new showdown.Converter({simplifiedAutoLink: true});
+      } else if (testsuite[i].name === '#709.allow-whitespaces-after-end-in-metadata') {
+        converter = new showdown.Converter({metadata: true});
       } else if (testsuite[i].name === 'relativePathBaseUrl') {
         converter = new showdown.Converter({relativePathBaseUrl: 'http://my.site.com/'});
       } else {