tiny updates from the last two weeks

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/robustbase@573 694ef91d-65df-0310-b7bb-92e67a308ead
improvement of r568: preserving attributes

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/robustbase@574 694ef91d-65df-0310-b7bb-92e67a308ead