* Update linux_install.markdown

Grammar improvements, fixed typos.

* Update tutorials.markdown

Improvements in grammar.

* Update table_of_content_calib3d.markdown

* Update camera_calibration_square_chess.markdown

Improvements in grammar. Added answer.

* Update tutorials.markdown

* Update erosion_dilatation.markdown

* Update table_of_content_imgproc.markdown

* Update warp_affine.markdown

* Update camera_calibration_square_chess.markdown

Removed extra space.

* Update gpu_basics_similarity.markdown

Grammatical improvements, fixed typos.

* Update trackbar.markdown

Improvement for better understanding.

Invalid links and refences fixed.
SpaeseMat class documentation updated.

Added the "How to write a tutorial for OpenCV?" tutorial. Made some corrections to the feature2D TOC tree. Small visual improvements for the video-write.rst file. Deleted a definition file that served no purpose.

Added the "Similarity check (PNSR and SSIM) on the GPU" tutorial. Corrected an highgui TOC tree mistake.

Added the How to create videos with OpenCV Tutorial. Made some corrections to the feature2d, to get rid of some documentation build errors. 

Ok, now optimized the tutorial size for real. Made JPG/PNG optimization for all the images. Modified some tutorial files to follow these size optimizations. Now the tutorial PDF generated is 3.95MB, so enjoy!

2) Added a raw Latex page break directive after each TOC tree. (For the PDF tutorial look).
3) Two finished tutorials: 
   a) one describing how the Mat data structure works and its output capabilities (format function) (demonstration YouTube video included).
   b) one describing image scanning operations plus the LUT function (demonstration YouTube video included). 
   c) a basic filtering approach (plus multi row image scanning demonstration) in the work.

New structure (following the documentation) for the tutorials. Normalized image sizes for TOC display.