Add getMemoryUsage function, detection update moved in abstract lass, splitted execution time in pre-inf-post, other minors.

Signed-off-by: Micaela Verucchi <micaelaverucchi@gmail.com>

tests/yolo3_coco4/yolo3_coco4.cpp

@@ -15,6 +15,11 @@ int main() {
     tk::dnn::Yolo *yolo [3];
     #include "models/Yolo3.h"
 
+    // fill classes names
+    for(int i=0; i<3; i++) {
+        yolo[i]->classesNames = {"person" , "bicycle" , "car" , "motorbike" };
+    }
+
     // Load input
     dnnType *data;
     dnnType *input_h;