A color ramp of ncol+1 individual colors is plotted, starting
with the background color (= color 0).
When ncol = NULL a color ramp of 101 individual colors is
plotted. The color at the bottom is labeled by '0', the color at the
top by 'max'.
# NOT RUN {par(oma=rep(2,4))
layout(matrix(c(1,2),ncol=2),
width=c(lcm(par("csi")*5*2.54),1),
heights=1)
# }# NOT RUN {iplotLegend(IDPcolorRamp,ncol=15)
# }