Pick centers in KMeans++ with a probability proportional to their distance^2, instead of simple distance, to previous centers
Apply to KMeansIndex KMeanspp the same modification as in HierarchicalClusteringIndex
As some processed distances are already ^2, use template to select whether or not we have to ^2 in KMeanspp
Move templates in dist.h in order to share them between KMeansIndex and HierarchicalClusteringIndex classes.
modified BackgroundSubtractorMOG2::getBackgroundImage so that it can now work with gray-level images.
Update out.cpp

Fixed a bug with the cv::format(cv::Mat, ...) method for matrices with only one row

see http://answers.opencv.org/question/21201/cvformat-does-not-format-the-way-it-should/?answer=23945#post-id-23945 for details
increase epsilon for MOG2::getBackgroundImage test:

it uses float arithmetics
Merge pull request #2541 from JinoBetti:2.4
perf report: summary.py: added custom --regressions map
fixed C4505
doc typos
Merge pull request #2548 from jet47:gpu_mog2_test
Merge pull request #2551 from ilya-lavrenov:ocl_nonfree
Merge pull request #2553 from ilya-lavrenov:typo
OpenCV version++. OpenCV Manager version++.
Merge pull request #2554 from asmorkalov:ocv_249_version
disable gpu::GeneralizedHough compilation on gcc 4.7
disable GeneralizedHough tests on gcc 4.7
Merge pull request #2572 from jet47:gpu-generalized-hough
fix condition in CV_OperationsTest::operations1()