Fixed Transparent Image Bug

[f3lan]

Problem: If you are using the inner zoom mode and you want to zoom a transparent PNG image. The image is allways shown in the backgound of the zoomed image.

Solution: Set the opacity of the source element to 0 while zooming. By the mouseleave callback set the opacity back to 1.

[Bokkeman]

Thanks, but it would really help if you could submit a clean PR with JUST the lines implementing your opacity fix. This project looks like it's been abandoned, but that would at least make it easier for others to also find and implement the two lines of your fix.