adapt functions for irregular response (and bhist)

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/fdboost@84 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
add spectral data on fossil fuels with the corresponding vignette

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/fdboost@85 edb9625f-4e0d-4859-8d74-9fd3b1da38cb