Stock level notify 0 no email

Hi,

Yes ; when the field is let empty, the feature is deactivated.
And in PHP, when you let a field empty or you put the value "0" ; it gave the same result when using the PHP function "empty".
So the minimum value authorized for that setting is "1".

Here the beginning of the function "checkQuantity" in the HikaSerial pack class

	public function checkQuantity(&$pack) {
		if(empty($pack->pack_params->stock_level_notify) || $pack->pack_params->stock_level_notify <= 0)
			return true;