The *.R files are some tests done to try out ideas for labeling lines drawn by mapContour(). There is no intention to reproduce the full features of the basic R function contour(), but the hope is to provide at least crude functionality.

If things seem promising, they may be incorporated into R/map.R, perhaps with the detailed work being done in a C function, for speed.

The numbers in the filenames show the evolution of my tests.

-- Dan Kelley, Feb 2019.