[R] set linetype with plotCI

[JeeBee]

Sorry, the plot_linetypes[1] is a debugging leftover.
It's plot_linetypes[graph_idx] in my actual code ...
And plot_linetypes is just the sequence 1,2,3,4... etc

> plotCI(
> 	x = xvals.f[sorted],
> 	y = yvals.f[sorted],
> 	xlim = c(xmin, xmax), ylim = c(ymin, ymax),
> 	pch = plot_symbols[graph_idx], type = "b",
>         lty = plot_linetypes[1],
> 	col = plot_colors[graph_idx], 
>         barcol = plot_colors[graph_idx], uiw = NA,
> 	xlab = "", ylab = "",
> 	add = (plot_cnt > 0)
> )