Problem with min/max in rotation calculation.

Let's say my settings are ```{max: 200, min: 100}``` and not ```{max: 100, min: 0}```

Then ```_range = 200-100 = 100```. But my values are e.g. 150, 130, 190... So this ```if (val < _range)``` will always be false.

I think my change fixes this.

Thanks for this awesome jQuery plugin btw. :)