The state is saved after the crop tool emits CropTool::done and gets
recalled if a new CropTool is created. The state also gets reset by
hitting the newly added reset button in the QDialogButtonBox of the
CropTool. The state also gets reset if the saved crop rectangle is
not within the image which is about to be cropped.
The use case for this is cropping the multiple images to the same
area. Like removing boarders of a series of pictures taken in a