Marking sub-intervals of multimodal highest density intervals

Here's a small aesthetic fix for the program BernGrid.R, so that it marks all interior end points of sub-intervals in a multimodal highest density interval.

For example, Figure 6.4 (p. 107) shows the posterior HDI with only the lowest and highest points marked by vertical lines (even though there is a horizontal "water level" that shows the subintervals):

The new program puts vertical lines at all the interior sub-interval end points, like this:

Is that exciting or what?!? If you just gotta have it, you can get it from the usual program repository. Get the files BernGrid.R, BernGridExample.R, and openGraphSaveGraph.R.