- added HAL documentation support
- added documentation to HAL replacement interface
- updated several HAL functions in imgproc module

Extension of the camera distortion model for tilted image sensors (Scheimpflug condition) including test

Add py_hdr tutorial under py_tutorials\py_photo.
This tutorial is similar to the one which is given at the C++ tutorials.

adding missing images from python tutorials, like chessboard.png, simple.jpg, home.jpg, fly.png, ...

Explicit link to 2.4 docs

Added note to point out code is for version 3.0 despite compatibility of
tutorial > version 2.0

The URL http://www.nptel.iitm.ac.in/courses/106108057/26 under Additional Resource section gives a 404. I've added the updated one i.e. http://www.nptel.ac.in/courses/106108057/26