Fix access to self.camera_number

trackmultiplefaces.py

@@ -228,7 +228,8 @@ class facetracker:
                                 add_warning_message):
 
         #Open the webcame device at camera_number
-        capture = cv2.VideoCapture(camera_number)
+        print("camera_number: ", self.camera_number)
+        capture = cv2.VideoCapture(self.camera_number)
 
         FULLSCREEN = False