- found a (remote) edge case for drift report, now mitigated
- associated with the new categorylist[0] convention for storing normalization_dict
- associated with cases where orig categorylist[0] != new categorylist[0]
- also a few other remote edge cases for drift report identified from runing comprehensive valications
- including edge cases associated with None / nan conversion and edge case case for null transform
- in the process performed some variable naming cleanup for drift report assembly
- had aggregated lists of returnedcolumns and newreturnedcolumns, but was refering to an entry in newreturnedcolumns as returncolumn, which was kind of confusing
- now referring to entry in newreturnedcolumns as newreturnedcolumn
- also revised the source column drift stat assembly heuristic for categoric features, increasing the heuristic threshold from 500 to 5000