Merge pull request #13188 from alalek:samples_rename

* samples: rename starter_imagelist.cpp

* samples: rename intelperc_capture.cpp => videocapture_intelperc.cpp

* samples: rename openni_capture.cpp => videocapture_openni.cpp

* samples: rename image_sequence.cpp => videocapture_image_sequence.cpp

* samples: rename gstreamer_pipeline.cpp => videocapture_gstreamer_pipeline.cpp

* samples: rename autofocus.cpp => videocapture_gphoto2_autofocus.cpp

* samples: rename live_detect_qrcode.cpp => qrcode.cpp

doc/tutorials/videoio/intelperc.markdown

@@ -78,5 +78,5 @@ there are two flags that should be used to set/get property of the needed genera
     flag value is assumed by default if neither of the two possible values of the property is set.
 
 For more information please refer to the example of usage
-[intelperc_capture.cpp](https://github.com/opencv/opencv/tree/3.4/samples/cpp/intelperc_capture.cpp)
+[videocapture_intelperc.cpp](https://github.com/opencv/opencv/tree/3.4/samples/cpp/videocapture_intelperc.cpp)
 in opencv/samples/cpp folder.

doc/tutorials/videoio/kinect_openni.markdown

@@ -134,5 +134,5 @@ property. The following properties of cameras available through OpenNI interface
     -   CAP_OPENNI_DEPTH_GENERATOR_REGISTRATION = CAP_OPENNI_DEPTH_GENERATOR + CAP_PROP_OPENNI_REGISTRATION
 
 For more information please refer to the example of usage
-[openni_capture.cpp](https://github.com/opencv/opencv/tree/3.4/samples/cpp/openni_capture.cpp) in
+[videocapture_openni.cpp](https://github.com/opencv/opencv/tree/3.4/samples/cpp/videocapture_openni.cpp) in
 opencv/samples/cpp folder.

samples/cpp/starter_imagelist.cpp → samples/cpp/imagelist_reader.cpp

 /*
- * starter_imagelist.cpp
- *
  *  Created on: Nov 23, 2010
  *      Author: Ethan Rublee
  *
@@ -16,10 +14,7 @@
 using namespace cv;
 using namespace std;
 
-//hide the local functions in an unnamed namespace
-namespace
-{
-void help(char** av)
+static void help(char** av)
 {
   cout << "\nThis program gets you started being able to read images from a list in a file\n"
           "Usage:\n./" << av[0] << " image_list.yaml\n"
@@ -30,7 +25,7 @@ void help(char** av)
         "Using OpenCV version %s\n" << CV_VERSION << "\n" << endl;
 }
 
-bool readStringList(const string& filename, vector<string>& l)
+static bool readStringList(const string& filename, vector<string>& l)
 {
   l.resize(0);
   FileStorage fs(filename, FileStorage::READ);
@@ -45,7 +40,7 @@ bool readStringList(const string& filename, vector<string>& l)
   return true;
 }
 
-int process(vector<string> images)
+static int process(const vector<string>& images)
 {
     namedWindow("image", WINDOW_KEEPRATIO); //resizable window;
     for (size_t i = 0; i < images.size(); i++)
@@ -53,13 +48,11 @@ int process(vector<string> images)
         Mat image = imread(images[i], IMREAD_GRAYSCALE); // do grayscale processing?
         imshow("image",image);
         cout << "Press a key to see the next image in the list." << endl;
-        waitKey(); // wait indefinitely for a key to be pressed
+        waitKey(); // wait infinitely for a key to be pressed
     }
     return 0;
 }
 
-}
-
 int main(int ac, char** av)
 {
   cv::CommandLineParser parser(ac, av, "{help h||}{@input||}");

samples/cpp/intelperc_capture.cpp → samples/cpp/videocapture_intelperc.cpp

-// testOpenCVCam.cpp : Defines the entry point for the console application.
-//
-
 #include "opencv2/videoio.hpp"
 #include "opencv2/highgui.hpp"