multiple shortname expression characters

[mmaiers-nmdp]

Here are cases (in 3.44.0) where there are multiple expression characters in the same group defined by a shortname.

Technically if we want to support things like A01:01N and A01:01L then there will need to be multiple lists generated from a single allele (who_group)

{'N', 'L'}
expression chars found in:  A*02:01
{'L', 'Q'}
expression chars found in:  A*02:01:01
{'L', 'Q'}
expression chars found in:  A*24:02
{'L', 'Q'}
expression chars found in:  A*24:02:01
{'L', 'Q'}
expression chars found in:  A*31:01
{'N', 'Q'}
expression chars found in:  A*31:01:02
{'N', 'Q'}
expression chars found in:  B*15:01
{'N', 'Q'}
expression chars found in:  B*15:01:01
{'N', 'Q'}
expression chars found in:  B*44:02
{'S', 'Q'}
expression chars found in:  B*44:02:01
{'S', 'Q'}
expression chars found in:  C*07:02
{'N', 'Q'}
expression chars found in:  C*07:02:01
{'N', 'Q'}
expression chars found in:  C*15:02
{'N', 'Q'}
expression chars found in:  C*15:02:01
{'N', 'Q'}```

[pbashyal-nmdp]

Fixed with #159