blog + groups fix

navigationlib.php

        if (has_capability('moodle/course:viewparticipants', $this->page->context)) {
            $participants = $coursenode->add(get_string('participants'), new moodle_url('/user/index.php?id='.$course->id), self::TYPE_CONTAINER, get_string('participants'), 'participants');
            $currentgroup = groups_get_course_group($course, true);
            if ($course->id == SITEID) {
                $blogparams = array('courseid' => '');
            } else if ($course->id && !$currentgroup) {
                $blogparams = array('courseid' => clean_param($course->id, PARAM_INT));
            } else {
                $blogparams = array('group' => clean_param($currentgroup, PARAM_INT));
            }
            if (($CFG->bloglevel == BLOG_GLOBAL_LEVEL or ($CFG->bloglevel == BLOG_SITE_LEVEL and (isloggedin() and !isguestuser())))
               and has_capability('moodle/blog:view', get_context_instance(CONTEXT_SYSTEM))) {
                $blogsurls = new moodle_url('/blog/index.php', $blogparams);
                $participants->add(get_string('blogscourse','blog'), $blogsurls->out());
            }
            if (!empty($CFG->enablenotes) && (has_capability('moodle/notes:manage', $this->page->context) || has_capability('moodle/notes:view', $this->page->context))) {
                $participants->add(get_string('notes','notes'), new moodle_url('/notes/index.php', array('filtertype'=>'course', 'filterselect'=>$course->id)));
            }
        } else if (count($this->extendforuser) > 0 || $this->page->course->id == $course->id) {
            $participants = $coursenode->add(get_string('participants'), null, self::TYPE_CONTAINER, get_string('participants'), 'participants');
        }