Suggest to remove Summary for individuals Summary statistics

[lenthomas]

The summary function for ds (which in turn calls summary.dht) by default gives a table of summary statistics for individuals:

library(Distance)
data(ClusterExercise)
groups <- ds(ClusterExercise, key="hr")
summary(groups)

gives:

However, the encounter rate and associated error given under individuals (circled) is misleading, as this is not used in calculating density of individuals. Users may be tempted to take the CV from here, for example, and try to use it to get the CV in density through the delta method, but this will not work (since it's the CV on cluster encouter rate that is relevant).

I suggest it get removed (and the final table have se.mean and possibly cv.mean added, so there is no loss of useful information).

[lenthomas]

Regarding my last suggestion, @dill tells me that se.mean is not shown in the last table unless the Buckland et al. variance estimator is used, which I think makes sense. So I withdraw that suggestion. I still think the summary for individuals table should be removed though.

[lenthomas]

Suggestion is to change the print method but not change the summary object (so it does not break dsims).