unconditional density bandwidths now have a member called "timing",
which contains the number of seconds required to compute the last
hit of the objective function
timing added for least-squares unconditional density
added timing for unconditional distribution bandwidths
added timing for conditional densities
added timing support for conditional distributions
timing support added for regression
Merge branch 'master' of https://github.com/JeffreyRacine/R-Package-np