0029787: Avoid in presentation edges of certain continuity class

0029787: Avoid in presentation edges of certain continuity class

A new flag theMostAllowedEdgeClass is passed to the methods StdPrs_ShadedShape: Add, FillFaceBoundaries. It describes the most allowed continuity class of edges that will be included into the presentation. The edges with more continuity will be ignored. By default, the value is CN, i.e. all edges are included into the presentation.
The new methods in AIS_Shape: SetMostContinuityClass, MostContinuityClass allows specifying the most allowed continuity class of edges at the level of shape's presentation