[R-sig-Geo] how to display a projected map on an rasterVis::layerplot?

[Tom Roche]

https://stat.ethz.ch/pipermail/r-sig-geo/2013-February/017531.html
> How to convert from a simple (x,y) matrix (as produced by
> M3::get.map.lines.M3.proj) to a SpatialLines, or to coordinates
> consumable by latticeExtra::layer?

One way to do this, though ugly, is the current answer @

http://stackoverflow.com/questions/14865507/how-to-display-a-projected-map-on-an-rlatticelayerplot

I.e., "fix" the coordinates in the `state.map` obtained from
`maps::map`, using the linear IOAPI transform, and process that into a
SpatialLines as previously--see code and plot @ link above.

Is there a cleaner way to do this?