To avoid warning when running R CMD CHECK (no visible global function
definition for 'subject'), import the packages np, quantreg, and rgl
in Imports: (DESCRIPTION) and NAMESPACE, remove require() calls in R
code, add np.messages inclusion in zzz.R (will not be needed when/if
npglpreg() migrates to the np package). Version number bumped up, no
issues remaining with R CMD CHECK --as-cran. Demos all check out.