polish doc, and add implementation of trivial getter (remark of Pierre)

Stream_lines_2/doc/Stream_lines_2/CGAL/Stream_lines_2.h

@@ -101,12 +101,12 @@ void update();
 /*! 
 returns the separating distance. 
 */ 
-void get_separating_distance(); 
+FT get_separating_distance() const; 
 
 /*! 
 returns the saturation ratio. 
 */ 
-void get_saturation_ratio(); 
+FT get_saturation_ratio() const; 
 
 /*! 
 prints the streamlines to an ASCII file: line by line, and point by point. 

Stream_lines_2/doc/Stream_lines_2/CGAL/Triangular_field_2.h

@@ -6,7 +6,7 @@ namespace CGAL {
 
 This class provides a vector field specified by a set of sample points 
 defined on a triangulated domain. All sample points are inserted to a 
-`Delaunay triangulation`, and for each point `p` in the domain 
+Delaunay triangulation, and for each point `p` in the domain 
 located in a face `f`, its vector value is interpolated from the 
 vertices of the face `f`. 
 
@@ -45,13 +45,13 @@ typedef StreamLinesTraits_2::Vector_2 Vector_2;
 /// @{
 
 /*! 
-Defines the points in the range 
+Defines the points in the range `[first_point, last_point)` 
-`[first_point, `last_point) 
+as the sample points of the triangular field, with the corresponding number of vectors started at `first_vector`. 
-as the sample points of the grid, with the corresponding number of vectors started at `first_vector`. 
+\tparam PointInputIterator must be an input iterator with the value type `Point_2`. 
-\pre The `value_type` of `InputIterator1` is `Point_2`. 
+\tparam VectorInputIterator must be an input iterator with the value type `Vector_2`. 
-\pre The `value_type` of `InputIterator2` is `Vector_2`. 
 */ 
-Triangular_field_2( InputIterator1 first_point, InputIterator1 last_point, InputIterator2 first_vector); 
+mplate <class PointIterator1, class VectorInputIterator>
+Triangular_field_2( PointInputIterator first_point, PointInputIterator last_point, VectorInputIterator first_vector); 
 
 /// @}
 

Stream_lines_2/doc/Stream_lines_2/Concepts/VectorField_2.h

@@ -46,7 +46,7 @@ typedef Hidden_type Vector_2;
 /// @{
 
 /*! 
-Any constructor has to allow the user to fill the vector values (i.e. assign a vector to each position within the domain). 
+Any constructor has to allow the user to fill the vector values, i.e., assign a vector to each position within the domain. 
 */ 
 VectorField_2(); 
 
@@ -56,26 +56,25 @@ VectorField_2();
 /// @{
 
 /*! 
-returns 
+returns the bounding box of the whole domain. 
-the bounding box of the whole domain. 
 */ 
 Geom_traits::Iso_rectangle_2 bbox(); 
 
 /*! 
 returns the vector field value and the local density. 
-\pre `is_in_domain(p)` must be true. 
+\pre `is_in_domain(p)` must be `true`. 
 */ 
 std::pair<Vector_2,FT> get_field(Point_2 p); 
 
 /*! 
-returns true if the point p 
+returns `true` if the point `p` 
-is inside the domain boundaries, false otherwise. 
+is inside the domain boundaries, `false` otherwise. 
 */ 
 bool is_in_domain(Point_2 p); 
 
 /*! 
-returns the integration step at the point p (i.e. the distance between `p` and the next point in the polyline.). 
+returns the integration step at the point `p`, i.e., the distance between `p` and the next point in the polyline. 
-\pre `is_in_domain(p)` must be true. 
+\pre `is_in_domain(p)` must be `true`. 
 */ 
 FT get_integration_step(Point_2 p); 
 

Stream_lines_2/include/CGAL/Stream_lines_2.h

@@ -107,6 +107,17 @@ protected:
 public:
   void set_separating_distance(FT new_value){separating_distance = new_value;}
   void set_saturation_ratio(FT new_value){ saturation_ratio = new_value;}
+
+  FT get_separating_distance() const
+  {
+    return separating_distance;
+  } 
+
+  FT get_saturation_ratio() const
+  {
+    return saturation_ratio;
+  }
+
   void update()
     {
       ir = il = 0; // initialization