changes in hhh4():
- $se, $cov and $Sigma have names
- neOffsetFUN uses small environment (parent=empty) if weights are fixed
- some code tuning


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/surveillance@791 edb9625f-4e0d-4859-8d74-9fd3b1da38cb