Fix some errors
Optimize openCL version of reduce function
Change buffer cols count from 64 to 32
fix code in the kernel
Fix some errors
Removed useless multiplication by 4
Merge pull request #2792 from SpecLad:merge-2.4
Merge pull request #2793 from alalek:run_android_env
OCL: matchTemplate: changed perf test
Moved new kernels under conditional compilation to disable their build for 3-channel images; added condition to use new kernels only for images that are big enough
Merge pull request #2788 from alalek:icv_public
Updating missed defines in documentation

Updating missed defines in documentation. The new defines (in imgproc.hpp) state they have a prefix of COLOR instead of CV.
opencl opticaflow fix that enables buffer2image extension
2 fixed unassigned reshapes in em (#3674)
Merge pull request #2796 from berak:b_3674_24
Adding explicit variable conversion in ocl_medianFilter() to suppress build errors on Linux & Mac
Merge pull request #2797 from ElenaGvozdeva:ocl_MT
optimized index access
optimized cv::meanStdDev
optimized index calculation