[Plugin: simpleContact] user permissions

At the moment only an administrator is able to see the adminpanel and any incoming messages.

I already found this part in the simpleContact.php:

if (preg_match('!wp\-admin!', $_SERVER['PHP_SELF']))
{
	// Aktivierung des Plugins
	register_activation_hook(__FILE__, array($sc, 'activate'));

	add_action('admin_menu', array($sc, 'admin'));
	add_action('admin_head', array($sc, 'head'));
	add_action('init', array($sc, 'buttons'));

	add_filter('editable_extensions', array($sc, 'editableExtensions'));
}

How do I have to manipulate this part, so all users see the control panel? Or is there a better solution for it?