ApproxInt/ApproxInt_SvSurfaces.hxx : adding field myUseSolver in order to manage calculations of characteristics of intersection points.
ApproxInt/ApproxInt_MultiLine.gxx : implementation of using myUseSolver for treatment points of MultiLine.
ApproxInt/ApproxInt_ImpPrmSvSurfaces.gxx : implementation of using myUseSolver for case intersection of implicit and parametric surfaces.
Test cases added