Mesh scalar range editor

This code adds a button into the vtkDataMeshInteractor and 2 medDoubleParameters to modify the range of a mesh.
Thanks to this  "mapper3d->InterpolateScalarsBeforeMappingOn();", it also improves the quality of the mesh visualization, I think it is now like paraview (visually).
Some changes have been made to SetScalarBarLabelFormat in vtkImageView.cxx