Added publication information for Li, Ouyang, and Racine (2013),
`Categorical Semiparametric Varying-Coefficient Models'
tweaks
Merge branch 'master' of https://github.com/JeffreyRacine/R-Package-np
robustness tweaks to numerical search
changing search tolerances to (hopefully) more sensible values.
scaling the hessian to avoid bad initial probes on categorical lambda search
tweaks to initialize_nr_hessian so that initial probes of cv function
for continuous variables do not go out of range.
Merge branch 'master' into npRmpi