Add Mobilenet2SSDLite test

The new test works both with TensorRT and cuDNN. Preprocessing and
Postprocessing are missing. Add ClippedReLU (for ReLU6), groups for
Conv2d, additional bias for convolution.

Other minors:
-move the timer in the detector to measure all the
processing time for a given frame (both centernet and yolo);
-add int8 flag.

Signed-off-by: Micaela Verucchi <micaelaverucchi@gmail.com>
Davide Sapienza <sapienza.dav@gmail.com>

demo/demo/map.cpp

@@ -34,7 +34,7 @@ int main(int argc, char *argv[])
     char * labels_path = "../demo/COCO_val2017/all_labels.txt";
     bool show = false;
     bool write_dets = false;
-    int n_images = 1000;
+    int n_images = 5000;
     
     if(argc > 1)
         net = argv[1];