MDL-65987 mod_forum: Add string 'Advanced' for the advanced editor.

AMOS BEGIN
    CPY [advanced,moodle],[showadvancededitor,moodle]
   AMOS END

lang/en/moodle.php

@@ -1808,6 +1808,7 @@ $string['shortnameuser'] = 'User short name';
 $string['shortsitename'] = 'Short name for site (eg single word)';
 $string['show'] = 'Show';
 $string['showactions'] = 'Show actions';
+$string['showadvancededitor'] = 'Advanced';
 $string['showadvancedsettings'] = 'Show advanced settings';
 $string['showall'] = 'Show all {$a}';
 $string['showallcourses'] = 'Show all courses';

mod/forum/classes/post_form.php

@@ -291,7 +291,7 @@ class mod_forum_post_form extends moodleform {
                 // Additional attribs to handle collapsible div.
                 ['data-toggle' => 'collapse', 'data-target' => "#collapseAddForm"]);
             $buttonarray[] = &$mform->createElement('submit', 'advancedadddiscussion',
-                get_string('advanced'), null, null, ['customclassoverride' => 'btn-link']);
+                get_string('showadvancededitor'), null, null, ['customclassoverride' => 'btn-link']);
 
             $mform->addGroup($buttonarray, 'buttonar', '', array(' '), false);
             $mform->closeHeaderBefore('buttonar');

mod/forum/tests/behat/behat_mod_forum.php

@@ -156,7 +156,7 @@ class behat_mod_forum extends behat_base {
         // Navigate to forum.
         $this->execute('behat_general::click_link', $this->escape($forumname));
         $this->execute('behat_general::click_link', $buttonstr);
-        $this->execute('behat_forms::press_button', get_string('advanced'));
+        $this->execute('behat_forms::press_button', get_string('showadvancededitor'));
 
         $this->fill_new_discussion_form($table);
     }