isSRGB

Returns true if the color space is sRGB. Returns false otherwise.

This allows a little bit of tolerance, given that we might see small numerical error in some cases: converting ICC fixed point to float, converting white point to D50, rounding decisions on transfer function and matrix.

This does not consider a 2.2f exponential transfer function to be sRGB. While these functions are similar (and it is sometimes useful to consider them together), this function checks for logical equality.