Reduce to Shortnulls
Implement shortnulls behavior with new config variable set to True by default.
This will address things like DRB4*01:03N and DRB5*01:08N both in terms of accepting them as valid and also by expanding them as appropriate to the list of longer alleles that have the same expression character.
DRB5*01:08N is acceptable by WHO rules since all suballeles have N.
DRB4*01:03N is acceptable by WMDA (but not WHO) rules but this needs to be handled for things like HF analysis by expansion to something valid (vs rejection) to avoid bias
When there are multiple expression characters in the same group defined by a shortname create multiple shortnulls for the same WHO group. e.g.
{'N', 'L'} A*02:01
{'L', 'Q'} A*02:01:01
{'L', 'Q'} A*24:02
{'L', 'Q'} A*24:02:01
{'L', 'Q'} A*31:01
{'N', 'Q'} A*31:01:02
{'N', 'Q'} B*15:01
{'N', 'Q'} B*15:01:01
{'N', 'Q'} B*44:02