restore xaxs/yaxs on.exit if necessary

[zeileis]

Fixes #545

If yaxs and/or xaxs are set in draw_facet_window() they are now retored to their previous values. This fixes the behavior of the examples from the issue.

tinyplot(~ species, data = penguins, type = type_barplot())
tinyplot(1:10, pch = 19, cex = 2)

tinyplot(species ~ island, data = penguins)
tinyplot(1:10, pch = 19, cex = 2)

Note that there is no clipping anymore of the first/last point in the scatterplot.

[vincentarelbundock]

Thanks!

I reviewed the changes and they are very clean and straightforward, so will merge now.

I just added a simple snapshot test with a title so we can easily know what to look for in the snapshot.

[vincentarelbundock]

and a news item

[zeileis]

Cool, Vincent, thanks a lot! 🚀 I was too tired yesterday...

[grantmcdermott]

Thanks both!

I know there are a couple of other new PRs to look at. I'm hoping to get time closer to the weekend.