don't discard pure virtual methods in hdr_parser.py (was broken anyway)

maintain set of visited namespaces in CppHeaderParser
WARNING: REMOVED const name conversion (SomeConstName -> SOME_CONST_NAME), discussion needed

gen2.py reports headers it processes
cmake file restructured

removed contrib, legacy and softcsscade modules; removed latentsvm and datamatrix detector from objdetect. removed haartraining and sft apps.
some of the stuff will be moved to opencv_contrib module.
in order to make this PR pass buildbot, please, comment off opencv_legacy, opencv_contrib and opencv_softcascade test runs.

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

e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

* always use "argN" names for unnamed arguments
* honor space symbol between typename and "*", "&" symbols
* fix indent errors

adjust the header parser to support "public virtual" construction and make a tweak for multiple inheritance, fix potential memory problem with Python's IplImage.tostring() method (ticket #1486)

updated feature_homography.py sample to use new features

upgraded to FLANN 1.6. Added miniflann interface, which is now used in the rest of OpenCV. Added Python bindings for FLANN.

- improved CV_IN_OUT/CV_OUT handling for generated Python/Java wrappers

a lot of small corrections to bring down the number of undocumented functions, reported by the script; added em.cpp sample

started work on API & doc synchronization (in particular, Mat& => Input/OutputArray in the descriptions)