added test for bug #1448 and hopefully fixes the bug #2898
increased time limits in perf tests
increased epsilon in sanity test
disable tests that requires video support if it is not available
fixed minMax perf test
Turn on OpenCL by default
Refactor OpenCL search
Allow OpenCL acceleration in every OpenCV module
Move OpenCL SURF to nonfree module
SURF accuracy test is moved to nonfree
Trying to make ocl surf work

1. Added more sync to reduction.
2. Turned off Image2D feature. Probably its support is not detected correctly.
3. Temporary disabled descriptor tests - can't localize a problem of the ocl descriptor.
Refactor OpenCL initialization and allow to use ocl module witout explicit setup
Disable crashing ocl tests
Move OpenCl SURF perf tests to nonfree and fix build of samples
Fixed wrong in row index of SSE implementation in prefilterXSobel function.
Fix build errors
Merge pull request #675 from jet47/gpu-test-fixes

GPU test fixes
Merge pull request #676 from vpisarev/svd_stuff

added test for bug #1448 and hopefully fixes the bug #2898
Merge pull request #686 from taka-no-me/stereobm_sobel

Fixed wrong index in prefilterXSobel function
Merge pull request #664 from taka-no-me/ocl

Move OpenCL SURF to nonfree module