Implemented Classifier and Wordspotter as two independent classes

Classifier implemented as an independednt class from the worspotter.
-Works both on CPU and GPU at expected top performance of 26ms per sample on a GTX 980Ti
-Simple demo for wordspoter added for cpp
-Interactiuve demo added for python

[Aruco] Fixed the spelling of Length in Samples

replaced images to 6x6_250

Updated README

[Aruco] Updated Charuco Diamond Detection Tutorial Readme

[Aruco] Updated Charuco Board  Detection Tutorial Readme

[Aruco] Updated Aruco Tutorials  Readme

[Aruco] Updated Aruco Tutorials  Readme

Added a new line at the end of file.

Update aruco_board_detection.markdown

Update aruco_calibration.markdown

Update aruco_detection.markdown

Update charuco_detection.markdown

Update charuco_diamond_detection.markdown

Update README.md

Update charuco_detection.markdown

Basic interfaces and a partial implementation of the Dense Inverse
Search (DIS) optical flow algorithm without variational refinement. Also
added a python benchmarking script that can evaluate different optical
flow algorithms on the MPI Sintel and Middlebury datasets and build
overall comparative charts.

Extensive changes to README.md opencv_contrib file to bring it up to date.

`lenght` --> `length`

structured_light:  python / java bindings

Update 2

ensure that the double pass through CMakeLists.txt files do not generate double output

see https://github.com/Itseez/opencv/issues/6370