Bug: extra slash breaking validation

Hi there,
I found a bug in your plugin that breaks HTML validation. When you set a custom class, the widget opening tag (i.e. <section>) gets an extra / and it becomes an invalid self-closing tag (i.e. <section class="..."/> instead of <section class="...">).

The problem is generated by the following line:

$params[0]['before_widget'] = preg_replace('/">/', " {$option_name[$number]['simple_widget_css_class']}\"/>", $params[0]['before_widget'], 1);

that should be:

$params[0]['before_widget'] = preg_replace('/">/', " {$option_name[$number]['simple_widget_css_class']}\">", $params[0]['before_widget'], 1);

https://wordpress.org/plugins/simple-widget-classes/