Fix for Shadowbox popup duplicity NEEDED

The default popup system of images in Hikashop doesn't have that problem. So simply use the default one if you want.
You can also use an image zoom integration to have a zoom image instead of a popup image.

And if you really want to have another image popup system integrated, you can simply develop a small integration with whatever popup system you want.

We have on our todo list that as we actually want to have our own popup system and properly handle that too in the process but that won't be for the short or middle term as there are alternatives, that it works fine by default, that you can potentially develop an alternative yourself, and that we are working on other more pressing needs.