minHeight & minWidth

I saw that you closed some issues related to minHeight & minWidth and i understand your point.
But I think this is a quite common requirement for a cropping tool. Often you know the minimum size of your image (e.g. after an upload) and IMHO it is reasonable to leave it up to the developer to make sure the minimum size is matched.
As I need these options and your cropping tool is one of the best out there I decided to fork it, even if you might reject my pull request. :)