exclude IlmImf/b44ExpLogTable.cpp from the build,

it's used originally to generate IlmImf/b44ExpLogTable.h, but not nessecary for the library.(probably only here for documentation

when included with static linking it introduces a problem with multiple definitions of main()

Move OpenCL SURF to nonfree module

Fixed wrong index in prefilterXSobel function

added test for bug #1448 and hopefully fixes the bug #2898

GPU test fixes

repaired std::string handling

1. Added more sync to reduction.
2. Turned off Image2D feature. Probably its support is not detected correctly.
3. Temporary disabled descriptor tests - can't localize a problem of the ocl descriptor.