Fix the sorting kernels used in the CenterNet pre and post-processing.

This commit moves the kernels in the correct sub-directory.
It creates new header file for Thrust kernels. It splits the
kernels into two files: 'normalize.cu' contains CenterNet
pre-processing operations, 'postprocessing.cu' contains the
CenterNet post-processing operations.

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

include/tkDNN/CenternetDetection.h

@@ -11,7 +11,7 @@
 
 #include "DetectionNN.h"
 
-#include "sorting.h"
+#include "kernelsThrust.h"
 
 
 namespace tk { namespace dnn {