Only requests likelihood statistic (LIKE) for Normal response models (otherwise get bug in debugmode due to missing values being replaced by INF, and so further model fits by the user via the MLwiN GUI result in error).

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/r2mlwin@80 edb9625f-4e0d-4859-8d74-9fd3b1da38cb