Suggestion: mention rows with all NA's

[paulfeitsma]

When using the data frame summary I encountered a dataset which had rows with only empty columns (NA's). It would be handy to mention this when this occurs on the top of the page at the data frame summary.

[dcomtois]

Not too sure about this one... I imagine this would be displayed in the heading section, but I don't want this section to be too lengthy... I'll leave open and see if other users request it.