add downscale utility functions: roundPowerOfTwoLargestEnclosed, roundPowerOfTwoSmallestEnclosing, downscalePowerOfTwoLargestEnclosed, downscalePowerOfTwoSmallestEnclosing
add downscale utility functions: roundPowerOfTwoLargestEnclosed, roundPowerOfTwoSmallestEnclosing, downscalePowerOfTwoLargestEnclosed, downscalePowerOfTwoSmallestEnclosing

Endika/Natron,Endika/Natron,Endika/Natron