Added Laplace, Canny and Sobel samples in tutorial cpp code

samples/cpp/tutorial_code/ImgTrans/Laplace_Demo.cpp

@@ -0,0 +1,56 @@
+/**
+ * @file Laplace_Demo.cpp
+ * @brief Sample code showing how to detect edges using the Laplace operator
+ * @author OpenCV team
+ */
+
+#include "opencv2/imgproc/imgproc.hpp"
+#include "opencv2/highgui/highgui.hpp"
+#include <stdlib.h>
+#include <stdio.h>
+
+using namespace cv;
+
+/**
+ * @function main
+ */
+int main( int argc, char** argv )
+{
+
+  Mat src, src_gray, dst;
+  int kernel_size = 3; 
+  int scale = 1;
+  int delta = 0;
+  int ddepth = CV_16S;
+  char* window_name = "Laplace Demo";
+
+  int c;
+
+  /// Load an image
+  src = imread( argv[1] );
+
+  if( !src.data )
+    { return -1; }
+
+  /// Remove noise by blurring with a Gaussian filter
+  GaussianBlur( src, src, Size(3,3), 0, 0, BORDER_DEFAULT );
+
+  /// Convert the image to grayscale
+  cvtColor( src, src_gray, CV_RGB2GRAY );
+
+  /// Create window
+  namedWindow( window_name, CV_WINDOW_AUTOSIZE );
+
+  /// Apply Laplace function
+  Mat abs_dst;
+
+  Laplacian( src_gray, dst, ddepth, kernel_size, scale, delta, BORDER_DEFAULT );
+  convertScaleAbs( dst, abs_dst );
+
+  /// Show what you got
+  imshow( window_name, abs_dst );
+
+  waitKey(0);
+
+  return 0;
+}