BUG NegativeBinomial add fit_regularized closes #1453 closes  #1454
    adjust test to handle extra parameter
CLN L1NegativeBinomialResults rename closes #1615,
    remove redundant `__init__`
TST fix negbin geometric test for fit_regularized
CLN: a few cosmetic changes
TST explicitely define k_extra in test class
REF add k_extra to NegativeBinomial, don't count it in df_model, df_resid
BUG: NegativeBinomial fix aic, bic for 'geometric', adjust tests
TST: adjust test, precision and start_params (failure on TravisCI)
TST: TestNegativeBinomialL1Compatability use desired as start_params
DOC: add comment in notes about not penalizing NegBin shape parameter [skip ci]
REF: NegativeBinomial fit_regularized, try regularized Poisson for start_params
BUG: fix if alpha is scalar,
TST: try standardized
REF: "is" None (not ==)
CLN: TST cleanup comment, unused code.
Merge pull request #1623 from josef-pkt/negbin_fit_regularized

BUG Negbin fit regularized missing