404 errors for plugin resources

Version 3.4.1 (and possibly version 3.4 too) returns 404 errors for the plugin resources on the WP settings page. This is due to an incorrect path. In the LiveChat.class.php file on line 52 you need to change:

$this->plugin_url = plugin_dir_url( __FILE__ ) . 'plugin_files';

to

$this->plugin_url = plugin_dir_url( __FILE__ );