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

You can test on this data : 
https://transfert.inria.fr/fichiers/abc107dd6efc2eb5b45fcc50b93f3225/2-Map_mesh_attributes.vtk
Don't parent your layouts here. They will be parented in the addRow method. This generates a message: QLayout: Attempting to add QLayout "" to QWidget "", which already has a layout