Saved, set, then unset timezone


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/blotter@1613 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Restore time zone after demo


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/blotter@1614 edb9625f-4e0d-4859-8d74-9fd3b1da38cb