Visible property defined as bool, should be integer

Hi, thanks for the hard work! I'm using this module in several projects. This issue is about the "Visible" property, which is implemented as a checkbox, when it should defined as an integer. This setting is important because it controls the number of items visible in the clipping area. Problem with it currently is that it always sets to "1" (it's a checkbox) and thus, the Jquery plugin always displays 1 item, when it should be allowed to display N items.

I found this issue to be blocking, and made me spend a lot of time trying to theme a very simple carousel.

So, I'm submitting a simple patch which is working in my environment, to make this property a scalar value instead of the faulty "always 1" value.

BTW, I think it should called "Visible", as per the JQuery plugin docs.