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.
perf report: summary.py: added custom --regressions map
fix condition in CV_OperationsTest::operations1()
Fix typos in old python wrapper documentation(Bug #3628)

Fixed spelling of CV_INTER_LINEAR flag in geometric_transformations.rst
remove unused variable in loadFromXML()
remove unused variable in HOGDescriptor::groupRectangles()
remove unused variable in findCorners_caller()
remove unused variable in ocl_moments()
remove unused variable in OCL_PERF_TEST_P()
remove unused variable in TEST_P()
remove unused variables in CV_KDTreeTest_CPP::findNeighbors()