legend does not respect pch from plot

```
library(imp.lattice)
x11()
.impenv$backend <- graphics_primitives
data(diamonds, package = "ggplot2")
p <- xyplot(price ~ carat, data = diamonds, groups = color,
    pch = 19, xlab = "carat", ylab = "price", 
    auto.key = list(space = 'right'))
p
```

The pch = 19 is not represented in the legend.
