When a cluster is empty for KMeans, it's better to give it the point from another cluster j that is the furthest one from center j.
modified OpenCL SURF API and the tests in 2.4.x to prove that it gives different from CPU results
made SURF_OCL default constructor parameters the same as SURF
modified SURF's performance test to test OpenCL version as well
fixed doc builder warnings; make sure the tests give reasonable results when OpenCL is not available
Implicit CUDA and OpenCL control for module definition added.

Feature allows to exclude CUDA or OpenCL optimizations at all even CUDA is used
on build. Exclusion of CUDA or OpenCL cut unwanted dependencies.
fix: use "cvAlloc" wrapper function for malloc.
Fixed an issue with weight assignment causing the resulting GMM weights to be unsorted in BackgroundSubtractorMOG2
improved performance of cv::ocl::minMax
changes for GFTT
improved performance of cv::ocl::countNonZero
improved performance of cv::ocl::sum
improved performance of bitwise ops
nonfree perf tests
typos
fix: use "cvAlloc" wrapper function for malloc.
Merge pull request #2475 from ilya-lavrenov:ocl_2.4_fix
missing () on Mat::type()
Viz::setViewerPose() - changed up-vector to down (common for Computer Vision & Odometry)
Merge pull request #2484 from berak:mat_doc_24