Option to copy the previous image's annotation(s) when going to the next one in image segmentation

[leonoverweel]

I'm currently labeling some image data that was captured sequentially (a few frames a second), in which the things I want to label often don't move too much between images. It'd be helpful if UDT had an option (togglable during labeling) to keep the previous image's annotations for the next image, so that I only have to tweak the bounding boxes slightly for consecutive frames instead of drawing them from scratch.

[seveibar]

This feature used to exist in the form of a "clone" button, I think it should be easy to re-add.

Thanks for the writeup, let's do it!