CONTRIB-3616 Book module do not display icon for book and chapter print

Credit goes to Peter Svec, thanks.

tool/print/lib.php

@@ -26,32 +26,32 @@
 defined('MOODLE_INTERNAL') || die;
 
 function booktool_print_extend_settings_navigation(settings_navigation $settingsnav, navigation_node $booknode) {
-     global $USER, $PAGE, $CFG, $DB, $OUTPUT;
+    global $USER, $PAGE, $CFG, $DB, $OUTPUT;
 
-     if ($PAGE->cm->modname !== 'book') {
-         return;
-     }
+    if ($PAGE->cm->modname !== 'book') {
+        return;
+    }
 
-     if (empty($PAGE->cm->context)) {
+    if (empty($PAGE->cm->context)) {
         $PAGE->cm->context = get_context_instance(CONTEXT_MODULE, $PAGE->cm->instance);
-     }
+    }
 
 
-     $params = $PAGE->url->params();
+    $params = $PAGE->url->params();
 
-     if (empty($params['id']) or empty($params['chapterid'])) {
-         return;
-     }
+    if (empty($params['id']) or empty($params['chapterid'])) {
+        return;
+    }
 
 
-     if (has_capability('booktool/print:print', $PAGE->cm->context)) {
-         $url1 = new moodle_url('/mod/book/tool/print/index.php', array('id'=>$params['id']));
-         $url2 = new moodle_url('/mod/book/tool/print/index.php', array('id'=>$params['id'], 'chapterid'=>$params['chapterid']));
-         $action = new action_link($url1, get_string('printbook', 'booktool_print'), new popup_action('click', $url1));
-         $booknode->add('', $action, navigation_node::TYPE_SETTING, null, null, new pix_icon('book', '', 'booktool_print', array('class'=>'icon')));
-         $action = new action_link($url2, get_string('printchapter', 'booktool_print'), new popup_action('click', $url2));
-         $booknode->add('', $action, navigation_node::TYPE_SETTING, null, null, new pix_icon('chapter', '', 'booktool_print', array('class'=>'icon')));
-     }
+    if (has_capability('booktool/print:print', $PAGE->cm->context)) {
+        $url1 = new moodle_url('/mod/book/tool/print/index.php', array('id'=>$params['id']));
+        $url2 = new moodle_url('/mod/book/tool/print/index.php', array('id'=>$params['id'], 'chapterid'=>$params['chapterid']));
+        $action = new action_link($url1, get_string('printbook', 'booktool_print'), new popup_action('click', $url1));
+        $booknode->add(get_string('printbook', 'booktool_print'), $action, navigation_node::TYPE_SETTING, null, null, new pix_icon('book', '', 'booktool_print', array('class'=>'icon')));
+        $action = new action_link($url2, get_string('printchapter', 'booktool_print'), new popup_action('click', $url2));
+        $booknode->add(get_string('printchapter', 'booktool_print'), $action, navigation_node::TYPE_SETTING, null, null, new pix_icon('chapter', '', 'booktool_print', array('class'=>'icon')));
+    }
 }
 
 /**