switched to new device layer in gpucodec module
If device does not support double, returns immediately.
Double floating points are not default supported by OpenCL.
fixed ocl::minMax
fixed ocl::countNonZero
Make libv4l support optional for testing purposes.
fixed ocl::sum, ocl::sqrSum, ocl::absSum
fixed ocl::phase
fixed ocl::setIdentity
fixed ocl::meanStddev and created accuracy test for this function
perf test: update error message about relative error
fixed compilation error "ambiguous symbol" on CUDA 5.0:

disabled Texture Reference API for old CUDA toolkits
fixed gridTransform overloads problems
used new device layer for cv::gpu::add
used new device layer for cv::gpu::subtract
used new device layer for cv::gpu::multiply
used new device layer for cv::gpu::divide
used new device layer for cv::gpu::absdiff
used new device layer in math per element operations
fixed assertion
used new device layer for cv::gpu::compare