removed long-gone members

Arrangement_on_surface_2/doc_tex/Arrangement_on_surface_2_ref/Arr_halfedge.tex

@@ -52,12 +52,6 @@ that return constant handles, iterators or circulators:
 \ccMethod{Vertex_handle target();}
     {returns a handle for the target vertex of \ccVar{}.}
 
-\ccMethod{bool source_at_infinity();}
-    {returns whether the source vertex of \ccVar{} lies at infinity.}
-\ccGlue
-\ccMethod{bool target_at_infinity();}
-    {returns whether the target vertex of \ccVar{} lies at infinity.}
-
 \ccMethod{Arr_halfedge_direction direction() const;}
     {returns the direction of the halfedge: \ccc{ARR_LEFT_TO_RIGHT} if
       \ccVar{}'s source vertex is lexicographically smaller than it