Tutorials for contrib modules

• aruco. ArUco marker detection (aruco module)
• bioinspired. Discovering the human retina and its use for image processing
• cvv. Interactive Visual Debugging of Computer Vision applications
• dnn. Build opencv_contrib with dnn module
• dnn. Load Caffe framework models
• face. Face Recognition with OpenCV
• line_descriptor. Line Features Tutorial
• sfm. Structure From Motion
• structured_light. Structured Light tutorials
• tracking. Customizing the CN Tracker
• tracking. Introduction to OpenCV Tracker
• tracking. Using MultiTracker
• ximgproc. Disparity map post-filtering
• ximgproc. Structured forests for fast edge detection
• ximgproc. Structured forest training
• xphoto. Training the learning-based white balance algorithm