[Rd] rowsum() may return a vector instead of a matrix (PR#3737)

[Thomas Lumley]

On Wed, 13 Aug 2003 brahm at alum.mit.edu wrote:

> If all rows are in the same "group", rowsum() returns a vector instead of a
> (1xN) matrix, contrary to documentation:
>

Yes, and it appears to be deliberate since rowsum.default() ends with
drop(rval), though I don't remember why it was this way.

Is there a strong preference for changing the function vs changing the
documentation?

	-thomas