added PWH(polygon pgn) CTOR and fixed outer boundary function description

Boolean_set_operations_2/doc_tex/Boolean_set_operations_2_ref/GeneralPolygonWithHoles_2.tex

@@ -43,6 +43,9 @@ the holes.
 \ccGlue
 \ccMethod{GeneralPolygonWithHoles_2 operator=(other);}{assignment operator.}
 
+\ccConstructor{GeneralPolygonWithHoles_2(General_polygon_2 & outer);}
+{constructs a general polygon with holes that has no holes using a given general polygon \ccc{outer} as the outer boundary.}
+
 \ccConstructor{template <class InputIterator>
 GeneralPolygonWithHoles_2(General_polygon_2 & outer,
                           InputIterator begin, InputIterator end);}
@@ -62,7 +65,7 @@ otherwise.}
 % ================
 
 \ccMethod{const General_polygon_2 & outer_boundary() const;}
-{returns the general polygon that represents the outer boundary. }
+{returns the general polygon that represents the outer boundary. Note that this polygon is not necessarily a valid (simple) general polygon because it may be relatively simple.}
 
 
 \ccMethod{Hole_const_iterator holes_begin() const;}