RObsDat: Preparing to move vignette into right location.


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/r-hydro@172 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
RObsDat: - moving vignettes to correct place
         - some update on tz handling


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/r-hydro@173 edb9625f-4e0d-4859-8d74-9fd3b1da38cb