receives the number of neighbors joined into each detected object

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.

CMake 2.8.11 removed linkage with CUDA driver library,
but it's used by gpu video encoding/decoding

setting 'char' to be signed by default since some tests fail when it's wrong (e.g. native compilation on ARM Linux)

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.

Yes, it's as ludicrous as it sounds, but it's still true. Bizarrely,
the previous commit makes CLAHE run about 10% slower on Android, even
though it doesn't even touch any CLAHE code. Splitting it off fixes that,
although the reason it does is a mystery for the ages.

It's cleaner when it's in its own file, anyway. ;=]

This should allow many algorithms to take advantage of more parallelization
technologies.

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.

In current implementation, this function only works when anchor point is
in the kernel center and kernel size supported is either 3x3 or 5x5.