Bug in barplot (PR#8738)

Hi

There seems to be a bug in barplot().  It occurs when specifying the
ylim argument.  It's best shown by example:

dat <- matrix(c(1,1,1,2,2,2,3,3,3),ncol=3)
barplot(dat, beside=TRUE)
X11()
barplot(dat, beside=TRUE, ylim=c(1,3))

As can be seem, drawing of the graph seems to discount the margins of
the plot.

I'm using R 2.2.1 on Windows

Thanks
Mick