Add different image sorting options

[kamuidev]

It would be really helpful to be able to assign/annotate images in random order rather than by filename. I have a set of images that consists of screenshots of different games, and they’re named in the order I took them, so they’re basically grouped by game. Without random annotating, this makes it hard to quickly get more variety for the model, since you’re basically forced to overfit if you want to train a new model before going through all annotation tasks because you have to slowly chug through each big section of images.