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

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

    * correct the part about fixed aspect
    * improve formatting
    * add snippet markers to source
    * replace inline code by @snippet
  - do not run calibration twice when using a imageList
  - make output consistent in itself (CamelCase vs no_camel_case) as well as with old camera calibrate sample
  - respect write extrinsic/ points flags
  - set the aspectRatio value when specified
  - fix writing of calibration settings. also update grammar.
  - fix intendation and remove some size_t -> int casts by using size_t

Fix a typo in first equation under method=CV_TM_CCOEFF.

The HAVE_DOC_GENERATOR variable was always true.

(cherry picked from commit 3d46c1f9)

Conflicts:
	doc/CMakeLists.txt