some improvements on tutorials

samples/cpp/tutorial_code/ImgTrans/Remap_Demo.cpp

@@ -23,10 +23,12 @@ void update_map( void );
 /**
  * @function main
  */
-int main( int, char** argv )
+int main(int argc, const char** argv)
 {
   /// Load the image
-  src = imread( argv[1], IMREAD_COLOR );
+  CommandLineParser parser(argc, argv, "{@image |../data/chicky_512.png|input image name}");
+  std::string filename = parser.get<std::string>(0);
+  src = imread( filename, IMREAD_COLOR );
 
   /// Create dst, map_x and map_y with the same size as src:
   dst.create( src.size(), src.type() );