o DOCUMENTATION: Added clarification to help("withTimeout") on the
  limitations of the function and when it is/is not possible to
  interrupt a function via timeouts.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/r-dots@2176 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Tweaks to help("withTimeout")

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/r-dots@2177 edb9625f-4e0d-4859-8d74-9fd3b1da38cb