added compute function to Feature2D (dirty workaround for #2699)
Fix for spurious assert in cv::compareHist

When comparing histograms that look like multi-channel images (e.g a 3D histogram, of 4x4x4 bins, might appear as a CV_32FC4 matrix), cv::compareHist would complain because it was expecting the matrix type() == CV_32F. Now we test matrix depth() == CV_32F instead.
Take account of multi-channel matrices when comparing histograms

Ensure that all channels are considered when comparing multi-channel histograms
Fix drawing documentation referring to C API macros
a few fixes of ocl::perf test cases
Fix ocl::pyrup kernel build on Mac.
Fix ocl::filter2D.
In current implementation, this function only works when anchor point is
in the kernel center and kernel size supported is either 3x3 or 5x5.
Adjust perf_filters, as this function only supports 3x3 kernel
fix a crash on Linux
Update ocl::surf_matcher sample.
The new sample adjust some parameters thus it should always be able to
calculate valid homography matrix when input is box.png and
box_in_scene.png.
Pure cpp surf and bfmatcher implementation is also added to show the user
its accuracy and performance.
Initialize OpenCL context at the end of getDevice call.
Added for better compatibility with the current samples/test cases.
User now will be able to initialize OpenCL context explicitly with
ocl::getDevice api.
This may be obsoleted in future releases.
Fix build error
Make AutoLock noncopyable (it would break on copying, anyway).
setting 'char' to be signed by default since some tests fail when it's wrong (e.g. native compilation on ARM Linux)
making the comment less ambigous
disabled samples with driver api
change a test image of pyrlk
Fix a bug of gfft.
When user provided corners buffer is big enough to be copied to from
tmpCorners_, we allow the buffer to be reused other than allocate a new
cl_mem object.
use GoodFeaturesToTrackDetector_OCL
fixed gpu module build on arm platform

links with CUDA driver library only if we use video encoding/decoding