Categorical names (again)

Do we really need, say, the reference level in the Treatment contrast? I'm not sure it adds enough information vs. the complexity it adds to the names to warrant inclusion. Thoughts? AFAICT, it only appears if you specify a reference level. If you specify one, then surely you know what you specified.

[~/]
[7]: dmatrix('~C(A, Treatment)', data=pd.DataFrame([['some really long name'], ['other name'], ['other name']], columns=['A']))
[7]: 
DesignMatrix with shape (3, 2)
Intercept  C(A, Treatment)[T.some really long name]
        1                                         1
        1                                         0
        1                                         0
Terms:
    'Intercept' (column 0)
    'C(A, Treatment)' (column 1)

[~/]
[8]: dmatrix("~C(A, Treatment('some really long name'))", data=pd.DataFrame([['some really long name'], ['other name'], ['other name']], columns=['A']))
[8]: 
DesignMatrix with shape (3, 2)
Intercept  C(A, Treatment('some really long name'))[T.other name]
        1                                                       0
        1                                                       1
        1                                                       1
Terms:
    'Intercept' (column 0)
    "C(A, Treatment('some really long name'))" (column 1)

Start by tracing the dmatrix entry point and the Treatment contrast named in the examples. Review how a specified reference level is incorporated into column names, then determine the intended naming behavior and add tests covering both default and explicitly specified reference levels.