cleanup of weibull confusion

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1054 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
fixed Weibull parametrization, see help(eventTime) for details

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/lava@1055 edb9625f-4e0d-4859-8d74-9fd3b1da38cb