Misc. typos

Found via `codespell -q 3 -I ../opencv-whitelist.txt --skip="./3rdparty"`

samples/cpp/train_HOG.cpp

@@ -204,7 +204,7 @@ int main( int argc, char** argv )
     const char* keys =
     {
         "{help h|     | show help message}"
-        "{pd    |     | path of directory contains possitive images}"
+        "{pd    |     | path of directory contains positive images}"
         "{nd    |     | path of directory contains negative images}"
         "{td    |     | path of directory contains test images}"
         "{tv    |     | test video file name}"

samples/cpp/tutorial_code/ml/introduction_to_pca/introduction_to_pca.cpp

@@ -1,6 +1,6 @@
 /**
  * @file introduction_to_pca.cpp
- * @brief This program demonstrates how to use OpenCV PCA to extract the orienation of an object
+ * @brief This program demonstrates how to use OpenCV PCA to extract the orientation of an object
  * @author OpenCV team
  */
 

samples/cpp/warpPerspective_demo.cpp

@@ -26,7 +26,7 @@ static void help(char** argv)
          "\tESC, q - quit the program\n"
          "\tr - change order of points to rotate transformation\n"
          "\tc - delete selected points\n"
-         "\ti - change order of points to invers transformation \n"
+         "\ti - change order of points to inverse transformation \n"
          "\nUse your mouse to select a point and move it to see transformation changes" << endl;
 }