experimental feature transbeta in bhist() for effects with 1/t \int ..., 
at the moment: plot function uses 1/t as well which does not make sense for t=0. 

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/fdboost@119 edb9625f-4e0d-4859-8d74-9fd3b1da38cb