Misc. ./samples typos

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

samples/python/mouse_and_match.py

@@ -67,7 +67,7 @@ if __name__ == '__main__':
     cv.setMouseCallback("gray", onmouse)
     '''Loop through all the images in the directory'''
     for infile in glob.glob( os.path.join(path, '*.*') ):
-        ext = os.path.splitext(infile)[1][1:] #get the filename extenstion
+        ext = os.path.splitext(infile)[1][1:] #get the filename extension
         if ext == "png" or ext == "jpg" or ext == "bmp" or ext == "tiff" or ext == "pbm":
             print(infile)
 

samples/python/plane_ar.py

@@ -5,7 +5,7 @@ Planar augmented reality
 ==================
 
 This sample shows an example of augmented reality overlay over a planar object
-tracked by PlaneTracker from plane_tracker.py. solvePnP funciton is used to
+tracked by PlaneTracker from plane_tracker.py. solvePnP function is used to
 estimate the tracked object location in 3d space.
 
 video: http://www.youtube.com/watch?v=pzVbhxx6aog

samples/python/video.py

@@ -8,7 +8,7 @@ frames from a camera of a movie file. Also the sample provides
 an example of procedural video generation by an object, mimicking
 the VideoCapture interface (see Chess class).
 
-'create_capture' is a convinience function for capture creation,
+'create_capture' is a convenience function for capture creation,
 falling back to procedural video in case of error.
 
 Usage: