add getoclcontext and getoclcommandqueue so that other opencl program can interactive with opencv ocl module
correct haar test cases
add face detection sample

add OCL 1.2 feature for setTo
bug fix of integral
replace the error code -217 with suitable MACRO
simplify tests, no need apply a new context for each test case
add more control for tests in utility.hpp

Retina module is now parallelized thanks to the TBB library. Speed increase expected on multicore plateforms

added GPU non local means brute force filter + tests

fixed some warnings