ReST directive was used. Also fixed some other ReST directives that were
not correct and removed some warnings during buildbot checks.

- Used lunix style slashes - works on most systems
- Removed all trailing whitespaces

Also, removed the one from modules/python/src2/cv.py and cleared its
executable bit, since it's not a script.

Invalid links and refences fixed.
SpaeseMat class documentation updated.

All errors were found by doc/check_docs2.py

Added a simple CMakeLists.txt to the facerec_samples, which are not included in the samples folder. Makes building these samples a lot easier.

added openfabmap code, contributed by Arren Glover. fixed several warnings in the new versions of retina filters

updated Retina module code for more flexible parallelisation : TBB parallel for loops are replaced by opencv parallel_for_ wrapper... compile error corrected

FaceRecognizer supports updating a model now. Documentation has been updated to reflect latest changes.

Updated the documentation to (1) reflect the latest changes and (2) answer some questions I were asked.

Fixed facerec_eigenfaces.cpp demo sample: it contained hardcoded values, which made wrong element access possible. Fixed unsigned integer/signed integer warnings in facerec.cpp.

Grammar and Formatting fixes. Added link to the Yale Facedatabase A. Added download directive links for linking to the sample source code samples.

Documentation for FaceRecognizer started (not added to toc of contrib/doc/contrib.rst yet). CSV file for the samples/cpp/facerec_demo.cpp added. Added some more exceptions to warn the user, when passing bad aligned data.

lot's of changes; nonfree & photo modules added; SIFT & SURF -> nonfree module; Inpainting -> photo; refactored features2d (ORB is still failing tests), optimized brute-force matcher and made it non-template.