AlexeyAB/darknet: Yolo v3 optimal

Features: fusion blocks: FPN, PAN, ASFF, BiFPN network modules: ResNet, CPS, SPP, RFB network architecture search: CSPResNext50, CSPDarknet53, SpineNet49, EfficientNetB0, MixNet-M activations: SWISH, MISH other features: weighted-[shortcut], Sigmoid scaling (Scale-sensitivity), Label smoothing, Optimal hyper parameters, Dynamic mini batch size for random shapes, Squeeze-and-excitation, Grouped convolution, MixConv (grouped [route]), Elastic-module data augmentation: MixUp, CutMix, Mosaic losses: MSE, GIoU, CIoU, DIoU detection layers: [yolo] (fixed iou_thresh), [Gaussian_yolo] detection on video (sequence of frames) - layers: [crnn] (convolutional-RNN), [conv_lstm] (Convolutional LSTM)