update ACEScc and ACESproxy to use terminology and functions from ACEScc and ACESproxy documents

address issue #39

Update ACEScc to use the formula defined in the ACEScc document, which includes compression of subnormals.
correct a typo for offset value in rgbMonitor ODTs

OFFSET was incorrectly typed as 0.55 instead of 0.055, which was contributing to the output of the forward transform looking exceedingly dark

fix #45