Correction of (X)HTML warnings in case of Advanced topics

Based on #3713 a  number of problems were solved, but also some new issues introduced.
- BaseDoxyfile.h see to it that the CGALAdvancedBegin is in a detailed part, so be sure to terminate the brief part by an extra carriage return
- commands like \pre, \note read till the beginning of the next section but a \htmlonly is not seen as a section separator, so insert an extra carriage return
- some places  missed an "Advanced" indicator, used the cgalAdvancedType here.

##Note
in Periodic_2_triangulation_2.h there appear to be a number of images that are a bit in thin air (Captions: "Insertion of a point on an edge." and "Insertion in a face."). Also just above these images theer are a number of functions that have documentation, but this is non-doxygen documentation and as such not seen by doxygen

Documentation/doc/resources/1.8.14/BaseDoxyfile.in

@@ -263,7 +263,7 @@ ALIASES                = "sc{1}=<span style=\"font-variant: small-caps;\">\1</sp
                          "cgalDebugBegin=\htmlonly[block] <div class=\"CGALDebug\"> <div>Debugging Support</div> \endhtmlonly ^^" \
                          "cgalDebugEnd=\htmlonly[block] </div> \endhtmlonly" \
                          "cgalDebugFunction=This is a function for debugging purpose." \
-                         "cgalAdvancedBegin=\htmlonly[block] <div class=\"CGALAdvanced\"> <div>Advanced</div> \endhtmlonly ^^" \
+                         "cgalAdvancedBegin=^^ \htmlonly[block] <div class=\"CGALAdvanced\"> <div>Advanced</div> \endhtmlonly ^^" \
                          "cgalAdvancedEnd=\htmlonly[block] </div> \endhtmlonly" \
                          "cgalAdvancedFunction=This is an advanced function." \
                          "cgalAdvancedClass=This is an advanced class." \

Periodic_2_triangulation_2/doc/Periodic_2_triangulation_2/CGAL/Periodic_2_triangulation_2.h

@@ -515,6 +515,7 @@ class Periodic_2_triangulation_2 : public Triangulation_cw_ccw_2
   Converts the current triangulation into the same periodic
   triangulation in the 1-sheeted covering space.
   \pre `is_triangulation_in_1_sheet()`
+
   \cgalAdvancedEnd
   */
   void convert_to_1_sheeted_covering();
@@ -991,6 +992,7 @@ class Periodic_2_triangulation_2 : public Triangulation_cw_ccw_2
   `f`. Face `f` is modified,
   two new faces are created. If the triangulation contains periodic copies, a point is inserted in all periodic copies.
   \pre The point in vertex `v` lies inside face `f`.
+
   \cgalAdvancedEnd
   */
   Vertex_handle insert_in_face(const Point& p, Face_handle f);
@@ -1000,6 +1002,7 @@ class Periodic_2_triangulation_2 : public Triangulation_cw_ccw_2
   \cgalAdvancedBegin
   Removes a vertex of degree three. Two of the incident faces are
   destroyed, the third one is modified. \pre Vertex `v` is a vertex with degree three.
+
   \cgalAdvancedEnd
   */
   void remove_degree_3(Vertex_handle v);
@@ -1023,6 +1026,7 @@ class Periodic_2_triangulation_2 : public Triangulation_cw_ccw_2
   `[edge_begin, edge_end]`. Returns a handle to the new vertex.
 
   \pre The triangulation is a triangulation of 1 sheet
+
     \cgalAdvancedEnd
   */
   template<class EdgeIt>
@@ -1038,6 +1042,7 @@ class Periodic_2_triangulation_2 : public Triangulation_cw_ccw_2
   and create new ones only when the sequence is exhausted.
 
   \pre The triangulation is a triangulation of 1 sheet
+
   \cgalAdvancedEnd
   */
   template<class EdgeIt, class FaceIt>

Point_set_3/include/CGAL/Point_set_3.h

@@ -1164,6 +1164,7 @@ class Point_set_3
     \return Returns a pair containing: the specified property map and a
     Boolean set to `true` or an empty property map and a Boolean set
     to `false` (if the property was not found).
+
     \cgalAdvancedEnd
   */
   template <class T>
@@ -1189,6 +1190,7 @@ class Point_set_3
 
     \note The normal property must have been added to the point set
     before calling this method (see `add_normal_map()`).
+
     \cgalAdvancedEnd
   */
   Vector_push_map normal_push_map ()

TDS_3/doc/TDS_3/Concepts/TriangulationDataStructure_3.h

@@ -125,6 +125,7 @@ data structure that only changes the vertex type. It has to define a type
 `Rebind_vertex<Vb2>::%Other` which is a <I>rebound</I> triangulation data structure, that is, the 
 one whose `TriangulationDSVertexBase_3` will be `Vb2`.
 \note It can be implemented using a nested template class.
+
 \cgalAdvancedEnd
 */ 
 template <typename Vb2> 
@@ -138,6 +139,7 @@ data structure that only changes the cell type. It has to define a type
 `Rebind_cell<Cb2>::%Other` which is a <I>rebound</I> triangulation data structure, that is, the 
 one whose `TriangulationDSCellBase_3` will be `Cb2`.
 \note It can be implemented using a nested template class.
+
 \cgalAdvancedEnd
 */ 
 template <typename Cb2> 

Triangulation/doc/Triangulation/CGAL/Triangulation_data_structure.h

@@ -81,18 +81,21 @@ data structure that only changes the vertex type. It has to define a type
 `Other` which is a <I>rebound</I> triangulation data structure with `Vb2`
 as vertex type.
 \note It can be implemented using a nested template class.
+
 \cgalAdvancedEnd
 */
 template <typename Vb2> 
 using Rebind_vertex = unspecified_type;
 
 /*!
+\cgalAdvancedType
 \cgalAdvancedBegin
 This template class allows to get the type of a triangulation
 data structure that only changes the full cell type. It has to define a type
 `Other` which is a <I>rebound</I> triangulation data structure with `Fcb2`
 as full cell type.
 \note It can be implemented using a nested template class.
+
 \cgalAdvancedEnd
 */
 template <typename Fcb2> 
@@ -113,6 +116,7 @@ The boundary is recognized by checking the mark of the full cells.
 This method is used by `Triangulation_data_structure::insert_in_hole()`. 
 s
 \pre same as `TriangulationDataStructure::insert_in_hole()` 
+
 \cgalAdvancedEnd
 
 */ 

Triangulation/doc/Triangulation/Concepts/TriangulationDataStructure.h

@@ -450,6 +450,8 @@ All vertices of cells of \f$ C\f$ are on \f$ \partial H\f$.
 \cgalFigureBegin{triangulationfiginserthole,insert-in-hole.png}
 Insertion in a hole, \f$ d=2\f$
 \cgalFigureEnd
+
+\cgalAdvancedEnd
 */
 template< class ForwardIterator > Vertex_handle
 insert_in_hole(ForwardIterator start, ForwardIterator end, Facet f);

Triangulation_2/doc/Triangulation_2/CGAL/Constrained_triangulation_plus_2.h

@@ -405,6 +405,7 @@ The simplification algorithm uses the following types and functions.
 /// @{
 
 /*!
+\cgalAdvancedType
 \cgalAdvancedBegin
 An iterator on the points of the original constraint
 before simplification steps are applied. The value type of this iterator is `Point`.
@@ -449,6 +450,7 @@ constraints based on a cost and stop function.
 \pre The vertex referred by vicq is not contained in any other constraint.
 \pre Let `vip` and `vir` be defined as `vip = std::prev(vicq)` and `vir = std::next(vicr)`.
 \pre The line segment between `*vicp->point()` and `*vicr->point()` must not intersect any constraint.
+
 \cgalAdvancedEnd
  */
 void