Warnings and exceptions

Everything superglm raises or warns with that a caller may want to catch or silence. Each docstring says when it fires and what to do about it.

superglm.PublicationModeError	The publication refit could not certify a penalized coefficient mode.
superglm.NearPoissonDispersionError	The Tweedie dispersion profile is too close to the Poisson limit to search globally.
superglm.RatingTableBaseNotRepresentableError	The exported base relativity is not a usable multiplier.
superglm.SeparationError	Refusal to fit (or certify) a design containing separated cells.
superglm.SeparationWarning	A term contains cells whose maximum-likelihood estimate is infinite.
superglm.NBThetaBoundWarning	The NB2 theta estimate sits on an active search bound.
superglm.FractionalFrequencyWeightWarning	A replication count that is not a whole number of observations.
superglm.PriorWeightLatticeWarning	A counting response or binomial weight lacks an exact probability law.