- improved plot method for varying coefficients (ylim now suitable) and
  base-learners of factor variables.
- confint now works with interaction effects (by) and spatial base-learners
- Fixed newly introduced bug in update()


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/mboost@787 edb9625f-4e0d-4859-8d74-9fd3b1da38cb