2. Two new NeonOptimized functions subtract_8u8u32f and subtract_8u8u8s were added

Refactored performance tests. TEST_CYCLE macro is renamed to TEST_CYCLE_N; SIMPLE_TEST_CYCLE is renamed to TEST_CYCLE; from now 100 iterations are default for performance tests

Fixed build for x64 with sse2 disabled; several improvements in performance testing framework; enabled SANITY_CHECK() for performance tests

Performance testing: added option to get list of all values for CV_ENUM; added perf test for cv::Sobel

Since there is no a standard functions cv::min and cv::max which has cv::Scalar argument, removed the performance tests, 
calling the functions cv::min and cv::max with cv::Scalar argument.
Instead of them two performance tests were created which call the functions cv::min and cv::max with 'double' argument.