Implementation of Quasi Dense Stereo algorithm. (#1941)

* initial commit.

* Remove license header.

* Fix python wrap flags

* Change std::string to cv::String, in function declarations, to resolve compilation issues.

* Add python wrapper extending header

* Fix python wrapper conflicts

* Fix implicit type conversions

* Change C API types and enums to C++.

* Remove redundant included headers and move wanted headers to src/precomp.hpp

* Remove saturate header

* Remove unnecessary python wrapping flags

* Removed defaults parameter header

* Split declaration and implementation of the class using Pimpl.

* Fix to comply with new public API.

* Remove unnecessary modules

* Fix maybe-uninitialized warnings on linux

* Migration to stereo module

* Remove CV_PROP_RW flag.

* Remove CV_EXPORTS flags from class members.

* Fix: Removed misplaced flag

* Remove empty lines.

* Move queue to private headers.

* Fix default arguments of public methods.

* Add authors information and switch to the compact version of license header.

* Reorganize and fix markdown files. Create a table of content and move tutorials in new directories. Modify samples and tutorials to use snippet and include Doxygen commands.

* Change argument name dMatch->denseMatch, to avoid confusion with cv::DMatch build-in type.

* Remove duplicate snippet.

* Fix: change vector resize to reserve.

* Fix: replace extensive license header with the compact version.