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

Changed to allow for ISO page size selection, checkerboard pattern now centres itself properly in middle of the page

It hasn't been used since f82c04f4. Also, the line adding the script had
an unneeded pathto call, so the script was being loaded from the wrong path
anyway.

Fixed difference in the given arguments to the ellipse function and the description after that

Fixed two more typos

Replaced unnecessary the with to

Conflicts:
	doc/tutorials/core/adding_images/adding_images.markdown
	doc/tutorials/core/basic_geometric_drawing/basic_geometric_drawing.markdown
	doc/tutorials/core/random_generator_and_text/random_generator_and_text.markdown
	modules/imgproc/include/opencv2/imgproc.hpp

Fixed difference in the given arguments to the ellipse function and the description after that

Fixed two more typos

Replaced unnecessary the with to

Conflicts:
	doc/tutorials/imgproc/imgtrans/hough_lines/hough_lines.rst