Fix zen_breadcrumb_title setting to use proper menu_get_active_item()

The feature "Append the content title to the end of the breadcrumb" is incompatible with devel theme developer which adds a span around the div of the breadcrumb. As a result the index -6 in

    $vars['breadcrumb'] = substr($vars['breadcrumb'], 0, -6) . $vars['title'] . '</div>';

is wrong (zen_preprocess_page() in template.php).

Not sure whether this is worth being fixed, but I thought I'd mention it here in case someone else runs into the same issue. The problem will naturally disappear when you disable devel theme developer (which should be the case on production sites or for anonymous users).