From Wouter:

  o RooFitResult
   
    - Export calculation of Schur complement of covariance matrix
      through method reducedCovarianceMatrix()


  o RooAbsReal

    - In linear calculation of partial error band use reduced covariance 
      matrix as calculated by RooFitResult.


  o RooCurve

    - Update Y-axis range in addPoint() rather than in ctor to
      capture updates to curve after construction, as e.g. done
      in construction of error band curves


git-svn-id: http://root.cern.ch/svn/root/trunk@29131 27541ba8-7e3a-0410-8455-c3a389f83636