Better handling of extrapolation

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bmhyd@32 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
fixed error in not setting allow.extrapolation

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bmhyd@33 edb9625f-4e0d-4859-8d74-9fd3b1da38cb