fulfil PR#15341

git-svn-id: https://svn.r-project.org/R/trunk@63309 00db46b3-68df-0310-9c12-caf00c1e9a41
comments on misuse of formatC

git-svn-id: https://svn.r-project.org/R/trunk@63311 00db46b3-68df-0310-9c12-caf00c1e9a41
formatC now discards class, to avoid invalid objects

git-svn-id: https://svn.r-project.org/R/trunk@63313 00db46b3-68df-0310-9c12-caf00c1e9a41