ENH: add MNLogit loglike_and_score
ENH: mle lbfgs now uses simultaneous loglike and score, tested with MNLogit
MAINT: change default maxiter to match docstring
MAINT: do not tell lbfgs to approximate the gradient if we are already passing it a score function
MAINT: restore approx_grad flag superpowers
Merge pull request #1161 from argriffing/mnlogit-loglike-score

add a fitting interface for simultaneous log likelihood and score, for lbfgs, tested with MNLogit