optimized cv::pow for integer power
minor ocl.cpp refactoring

fix for cv::LUT and cv::transpose
fixed
Merge pull request #2275 from ElenaGvozdeva:ocl_matchTemplate
Merge pull request #2268 from ilya-lavrenov:tapi_pow
Merge pull request #2252 from ilya-lavrenov:ocl_ref
Merge pull request #2234 from KonstantinMatskevich:ocl_tapi_hog
core/ocl: OpenCLBufferPool
fix memory leak for Mat::getUMat() operation
Merge pull request #2192 from alalek:buffer_pool
attempt to fix pure virtual call in Mat::deallocate
Merge pull request #2279 from alalek:fix_memory_leak_getumat
Merge pull request #2280 from ilya-lavrenov:attempt_pvc
Some tests for UMat
update