Rework deduped_preview method
This allows us to use it in more cases than just where we used the image icon. Now you supply either a icon struct or a string. Both will result in a hoverable link that will show the image in question. We also allowed for specifying URL as it's not always straight forward to programmatically figure out which URL is correct
At the same time we created a global javascript for the mouseover function. This code was duplicated a few times in the code so those were able to be removed now.
Please forgive me for having everything in one commit, but they are rather co-dependent and I didn't feel like needling out what could be split or not