TAPI: added perf test for stitching
TAPI: stitching, replaced Mat->UMat/_Array
features2d: workaround for 'utrainDescCollection' issue (PR #2142)
TAPI: stitching: improve warpers
TAPI: stitching: workaround for problem getUMat() call
TAPI: stitching: optimize exposure
TAPI: stitching: optimize compare operation
stitching: use BORDER_CONSTANT in warp
stitching: extend logging
TAPI: stiching: add custom OpenCL kernels for MultiBandBlender
stitching: allow to use dynamic DescriptorMatcher
TAPI: stitching: blender: fix OpenCL path & adjust test condition
tapi: stitching: fix documentation
ocl: workaround for synchronization issue in ::map()
core/ocl: CV_OCL_RUN macro improvements