Allow to read PNG image of color_type PNG_COLOR_TYPE_PALETTE with alpha channel
Correct reading PNG color type palette with or without alpha imread flags -1 or 1
Better not using pnginfo.h, using png_get_tRNS instead
using unsigned char instead of uint8_t to compile under windows
added a test for ocl::norm
fixer error with incorrect condition
removed NPP implementation
reorganize code for further modifiction
added custom implementation for nearest and linear interpolation
improved texture usage:

* use explicit extrapolation only for sub-matrixes
* use built-in interpolation for INTER_NEAREST mode
used global memory access for up-scaling
most of the performance tests was rewritten in google-test manner
the code was refactored and old test system code was removed
Merge pull request #1336 from jet47:gpu-resize
Merge pull request #1326 from ilya-lavrenov:perf_ocl
Merge pull request #1311 from leszekhanusz:png_palette_alpha
Bug #3238 Android sample image manipulations blinks in non-preview modes fixed.