pangomm: New API in pangomm 2.46

pangomm 2.52.0

New API in pangomm 2.46

Member Pango::Attribute::create_attr_allow_breaks (bool allow_breaks)
Member Pango::Attribute::create_attr_insert_hyphens (bool insert_hyphens)
Member Pango::Attribute::create_attr_overline (Overline overline)
Member Pango::Attribute::create_attr_overline_color (guint16 red, guint16 green, guint16 blue)
Member Pango::Attribute::create_attr_show (ShowFlags show)
Member Pango::Attribute::get_type_name (AttrType type)