wrong version of zero_to_twofivefive_simplest_norming()

[drcandacemakedamoore]

We seem to have put in an older (with a small bug) version of the zero_to_twofivefive_simplest_norming(). All image normalization functions should be tested and updated tonight (24/1/2022)

[drcandacemakedamoore]

Function and steps.py equivalent fixed and retested on develop. We need to retest and fix the other two main normalization functions (HistogramNormalize(Step), and the one in image_functions); then possibly push it all from develop.

[drcandacemakedamoore]

All currently fixed and tested on develop branch. Awaiting CI improvement before develop --> main

[drcandacemakedamoore]

Finished. We could actually add various normalization functions beyond linear and the typical throw-off-extremes used on radiological images...but for CXR it may be overkill