fixes handling of empty matrices in some functions (#11634)

* a part of PR #11416 by Yuki Takehara

* moved the empty mat check in Mat::copyTo()

* fixed some test failures

Added gradiantSize param into goodFeaturesToTrack API (#9618)

* Added gradiantSize param into goodFeaturesToTrack API

Removed hardcode value 3 in goodFeaturesToTrack API, and
added new param 'gradinatSize' in this API so that user can
pass any gradiant size as 3, 5 or 7.
Signed-off-by: Vipin Anand <anand.vipin@gmail.com>
Signed-off-by: Nilaykumar Patel<nilay.nilpat@gmail.com>
Signed-off-by: Prashanth Voora <prashanthx85@gmail.com>

* fixed compilation error for java test
Signed-off-by: Vipin Anand <anand.vipin@gmail.com>

* Modifying code for previous binary compatibility and fixing other warnings

fixed ABI break issue

resolved merged conflict

compilation error fix
Signed-off-by: Vipin Anand <anand.vipin@gmail.com>
Signed-off-by: Patel, Nilaykumar K <nilay.nilpat@gmail.com>

Signed-off-by: Vipin Anand <anand.vipin@gmail.com>
Signed-off-by: Prashanth Voora <prashanthx85@gmail.com>
Signed-off-by: Patel, Nilaykumar K <nilay.nilpat@gmail.com>

quickly corrected the previous refactoring of features2d: moved from set(SOME_PROP, val) to setSomeProp(val)

OpenCV with the refactored features2d compiles! contrib is broken for now; the tests are not tried yet

OpenCV with the refactored features2d compiles! contrib is broken for now; the tests are not tried yet

Conflicts:
	modules/core/include/opencv2/core/cuda.hpp
	modules/cudacodec/src/thread.cpp
	modules/cudacodec/src/thread.hpp
	modules/superres/perf/perf_superres.cpp
	modules/superres/src/btv_l1_cuda.cpp
	modules/superres/src/optical_flow.cpp
	modules/videostab/src/global_motion.cpp
	modules/videostab/src/inpainting.cpp
	samples/cpp/stitching_detailed.cpp
	samples/cpp/videostab.cpp
	samples/gpu/stereo_multi.cpp

This should allow many algorithms to take advantage of more parallelization
technologies.

All tests passed!

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

added dedicated <modname>_init.cpp files with initModule_<modname>() functions and all the relevant structures; made BackgroundSubtractorMOG/MOG2 derivatives from Algorithm; cleaned up MOG2 implementation and made it multi-threaded.

Suppressed hundreds of useless MSVC warnings (can be reenabled setting cmake variable ENABLE_NOISY_WARNINGS to ON). Fixed some of remaining warnings.

added initModule_features2d(). Possibly solved problem when the linker excludes seemingly unused detectors/descriptors.

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.

added improved ORB implementation, convex-convex polygon intersection, eigen2x2 low-level function ...

added read/write methods for SimpleBlobDetector and DenseFeatureDetector; added their creation to FeatureDetector::create method (#1290)