Better unpenalized var handling
Improved unpenalized var handling by conforming to approach taken in R's glmnet and gamlr, where an explanatory variable with a zero penalty factor is included in the base / null model that is used as a starting point for the regularization path.
The two following keyword arguments were added to allow us to compare in test/gammalasso.jl against gamlr:
stopearly
allows the user to disable early stopping of regularization pathstandardizeω
allows the user to disable standardization of penalty factors
These behaviors both happen by default in glmnet but not gamlr