Labels are added to the wrong axis in vioplot 0.5.0 when `horizontal=TRUE`

[csoneson]

Hi,

I'm plotting a horizontal vioplot with the following example code:

set.seed(123L)
vioplot::vioplot(rnorm(100), rnorm(50, 1, 2), horizontal = TRUE)

With vioplot 0.4.0, I get the following plot:

With vioplot 0.5.0, instead, I get this:

In the second plot, the group labels are added to the x-axis instead of the y-axis, and the y-axis labels are gone. With horizontal=FALSE, the plots look as expected.