https://github.com/AlexeyAB/darknet
https://pjreddie.com/darknet/yolo/ old: https://pjreddie.com/darknet/yolov1/ , https://pjreddie.com/darknet/yolov2/ https://timebutt.github.io/static/how-to-train-yolov2-to-detect-custom-objects/
git clone https://github.com/pjreddie/darknet