Added TensorRT8 support

- Migrated to TRT8 API, but I didn't really try maintaining old compatiblity. Lowest support now could be TRT6.
- Refractored some stuff that are bad C++ practices and made coding really hard, like including headers in namespaces or not using an include guard.
- Needed to move the yolo container outside tkdnn object, which means we now only have one and global. Deserialization in TRT8 doesn't happen in your object, but in the plugin itself so it couldn't access the yolo objects. I think the need to hold onto yolo layers itself is flawed and shouldn't be nessesarry.

src/yoloContainer.cpp

@@ -0,0 +1,41 @@
+#include "yoloContainer.h"
+#include "pluginsRT/YoloRT.h"
+
+namespace tk { namespace dnn {
+YoloContainer yoloContainer;
+
+nvinfer1::IPluginV2* YoloRTCreator::deserializePlugin(const char* name, const void* serialData, size_t serialLength) noexcept {
+  const char * buf = reinterpret_cast<const char*>(serialData),*bufCheck = buf;
+  int classes_temp = tk::dnn::readBUF<int>(buf);
+  int num_temp = tk::dnn::readBUF<int>(buf);
+  int n_masks_temp = tk::dnn::readBUF<int>(buf);
+  float scale_xy_temp = tk::dnn::readBUF<float>(buf);
+  float nms_thresh_temp = tk::dnn::readBUF<float>(buf);
+  int nms_kind_temp = tk::dnn::readBUF<int>(buf);
+  int new_coords_temp = tk::dnn::readBUF<int>(buf);
+
+  YoloRT *r = new YoloRT(classes_temp,num_temp,nullptr,n_masks_temp,scale_xy_temp,nms_thresh_temp,nms_kind_temp,new_coords_temp);
+
+  r->c = tk::dnn::readBUF<int>(buf);
+  r->h = tk::dnn::readBUF<int>(buf);
+  r->w = tk::dnn::readBUF<int>(buf);
+  for(int i=0; i<r->n_masks; i++)
+      r->mask[i] = tk::dnn::readBUF<dnnType>(buf);
+  for(int i=0; i<r->n_masks*2*r->num; i++)
+      r->bias[i] = tk::dnn::readBUF<dnnType>(buf);
+
+  // save classes names
+  r->classesNames.resize(r->classes);
+  for(int i=0; i<r->classes; i++) {
+          char tmp[YOLORT_CLASSNAME_W];
+    for(int j=0; j<YOLORT_CLASSNAME_W; j++)
+      tmp[j] = tk::dnn::readBUF<char>(buf);
+          r->classesNames[i] = std::string(tmp);
+  }
+  assert(buf == bufCheck + serialLength);
+
+  yoloContainer.yolos[yoloContainer.n_yolos++] = r;
+  return r;
+}
+
+}}