[request] a function to set previously saved x, y, width and height attribute

[MarcianoStikkelorum]

I would like to have an option/function to set a previously saved cropped image back into the cropper where the user has left off. This means that I need a way to set the x, y, width and height of the cropped area.

If you're open to pull requests, I can give it a shot myself and send you a PR from it.