Implements fast, scalable optimization algorithms for
fitting generalized principal components analysis (GLM-PCA) models,
as described in "A Generalization of Principal Components
Analysis to the Exponential Family" Collins M, Dasgupta S, Schapire RE
(2002, ISBN:9780262271738), and subsequently "Feature Selection
and Dimension Reduction for Single-Cell RNA-Seq Based on a Multinomial
Model" Townes FW, Hicks SC, Aryee MJ, Irizarry RA (2019)