fix integer overflow in  " Calloc((*n) * (*n) * (*p), double) "
(which seg.faulted) and give user friendly error message

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/nacopula@1080 edb9625f-4e0d-4859-8d74-9fd3b1da38cb