Added changes suggested by bug #3186 : fixing the unplugging of webcam
Added Kalman Filter of OpenCL version.
Removed whitespace.
fixed ocl::merge in case of 2 and types CV_32S and CV_32F
fixed HOG perf test
Merge pull request #1376 from StevenPuttemans:bugfix_3186
Merge pull request #1413 from melody-rain:2.4_kalman_filter
Merge pull request #1420 from ilya-lavrenov:ocl_perf_hog
Merge pull request #1417 from ilya-lavrenov:merge_fix