Define an area of a submitted image as the thumbnail

Since we are using a square grid view mode it would be great to be able to select what area of the image will appear as the thumbnail, there are a lot of pictures with half of the character's body/head missing or generally giving a bad representation of the picture in the preview. Let us choose, if the feature already exists, make it pop up automatically when submitting a new image.

That is all, have fun.