KWSys: Remove DateStamp

KWSys is no longer shared in projects via a server-side directory
symlink in CVS.  An automated nightly date stamp commit can no longer be
shared by multiple projects directly.  It needs a per-project replay
robot so the nightly commits end up needing N+1 robots instead of N.
Remove the DateStamp feature because it is no longer useful or
maintained by nightly commits.