message: Add ability to read thresh and nms_threshold from YOLO layer in YOLOV3 cfg file.
  Currently the thresh is hard-coded to be 0.2 and nms_threshold as 0.4.
diff: @@ -371,7 +371,7 @@ namespace cv {
  fused_layer_names.push_back(last_layer);
  }
  - void setYolo(int classes, const std::vector<int>& mask, const std::vector<float>& anchors)
  + void setYolo(int classes, const std::vector<int>& mask, const std::vector<float>& anchors, float thresh, float nms_threshold)
  {
  cv::dnn::LayerParams region_param;
  region_param.name = "Region-name";
  @@ -382,6 +382,8 @@ namespace cv {
  region_param.set<int>("classes", classes);
  region_param.set<int>("anchors", numAnchors);
  region_param.set<bool>("logistic", true);
  + region_param.set<float>("thresh", thresh);
  + region_param.set<float>("nms_threshold", nms_threshold);
  std::vector<float> usedAnchors(numAnchors * 2);
  for (int i = 0; i < numAnchors; ++i)
  @@ -646,6 +648,8 @@ namespace cv {
  {
  int classes = getParam<int>(layer_params, "classes", -1);
  int num_of_anchors = getParam<int>(layer_params, "num", -1);
  + float thresh = getParam<float>(layer_params, "thresh", 0.2);
  + float nms_threshold = getParam<float>(layer_params, "nms_threshold", 0.4);
  std::string anchors_values = getParam<std::string>(layer_params, "anchors", std::string());
  CV_Assert(!anchors_values.empty());
  @@ -658,7 +662,7 @@ namespace cv {
  CV_Assert(classes > 0 && num_of_anchors > 0 && (num_of_anchors * 2) == anchors_vec.size());
  setParams.setPermute(false);
  - setParams.setYolo(classes, mask_vec, anchors_vec);
  + setParams.setYolo(classes, mask_vec, anchors_vec, thresh, nms_threshold);
  }
  else {
  CV_Error(cv::Error::StsParseError, "Unknown layer type: " + layer_type);
  