singleclusterplot: single cluster plot
In Starr: Simple tiling array analysis of Affymetrix ChIP-chip data

This function is called by clusterplot

singleclusterplot(cluster,label=NULL,at=NULL,main = "",xlim=NULL,xlab = "", xaxt = "s",	xlabels = NULL, las = 1, ylim=NULL, ylab = "",fromto = c(0.05,0.95),colpal = "heat", nrcolors = 25,	outer.col="light grey",	add.quartiles = T)

`cluster`	an items x columns matrix with numerical entries. each item will define a line in the clusterplot
`label`	if multiple clusters should be plotted in one diagram, the cluster labels for each item are given in this vector
`at`	at which x-positions will the columns occur in the plot?
`main`	the title of the plot
`xlim`	xlimits, standard graphics parameter
`xlab`	x-axis legend, standard graphics parameter
`xaxt`	should an x axis be plotted at all? (="n" if not)
`xlabels`	text added as x-axis labels
`las`	las=1: horizontal text, la2=2: vertical text
`ylim`	ylimits, standard graphics parameter
`ylab`	y-axis legend, standard graphics parameter
`fromto`
`colpal`	either "red","green","blue" (standard colors), or a vector of colors that can be used instead of a standard color palette.
`nrcolors`	how many colors will the color palette contain?
`outer.col`	color of the outlier lines
`add.quartiles`	should the quartile lines be plotted (grey/black)?