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
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 #1326 from ilya-lavrenov:perf_ocl
Merge pull request #1311 from leszekhanusz:png_palette_alpha