link bug fix

- add multiple camera calibration tutorial
- code clean

upload an example data in tutorial

Fix for Bug 4074. This seems to be just a typo-error.

Fix for Bug #3633: do away with "quads [2][3] = 255;" The four lowest bits in each quads[i][j] correspond to the 2x2 binary patterns Q_1, Q_2, Q_3 in the NM paper [1] (see in page 4 at the end of first column). Q_1 and Q_2 have four patterns, while Q_3 has only two.

Fix for Bug 4074. This seems to be just a typo-error, because the Tesseract API can handle correctly with RGB images (double-checked and it works).

Interface and demo for disparity filtering, basic WLS implementation

Bugfix Normalization / Enhance "float/double" mode queries for DAISY.

Bug fix for feature extraction

BugFix & Enhance DAISY.

According to CartToPolar() function documentation, result angles could be in range (0..360). To prevent index overflow this check is important.

fixed several warnings in opencv_contrib (text, xfeatures2d)

fixed several warnings in opencv_contrib (text, xfeatures2d); added tesseract installation mini-guide in text/readme.md

Add rotation invariance option for BRIEF descriptor.

Added basic interface and demo for disparity filtering, added unoptimized fast weighted least
squares filter implementation. Current demo tests domain transform, guided and
weighted least squares filters on a dataset, measures speed and quality.

bugfix4269 included remarks in http://answers.opencv.org/question/59293/...

Added python support, updated Retina class documentation