lity in fitting.
  This class in addition to the TVirtualFitter provides the following functionality:
  <ul>
    <li>access direct to references to <tt>ROOT::Fit::FitResult</tt>  and <tt>ROOT::FitConfig</tt> objects via the member functions <tt>TBackCompFitter::GetFitResult()</tt> and <tt>TBackCompFitter::GetFitConfig()</tt>
    <li>Possibility to set the fit the fit function directly as a function pointer to a muldi-dimensional function interface instead of using the TMinuit FCN style API.
    <li>New meth