xplot: Generate cross-plot with kernel density estimates on axes
Description
Generate a cross-plot with kernel density estimates on axes. If multiple data points are superposed
in cross-plot, transparency of points reflects data density. Custom axes titles optional.
# NOT RUN {# random numbers from a normal distributionex1<-rnorm(1000)
# random numbers from an exponential distributionex2<-rexp(1000)
xplot(ex1,ex2)
# }