Introduce a new helper macro CGAL_VERSION_NUMBER

that computes the version number of a public release.
Much easier to use than reading the algorithm that computes it !

Developers_manual/doc_tex/Developers_manual/portability.tex

@@ -143,6 +143,12 @@ macros:
      Examples: for the public release 3.2.4 this number is 
      1030241000; for internal release 3.2-I-1, it is 1030200001.
      Note that the scheme was modified around 3.2-I-30.
+\item[\texttt{CGAL\_VERSION\_NUMBER(M,m,b)}], 
+     \index{CGAL_VERSION_NUMBER macro@{\tt CGAL\_VERSION\_NUMBER} macro}
+     -- a function macro providing computing the version number macro
+     from the M.m.b release version.  Note that the internal release
+     number is dropped here.  Example: {\tt CGAL\_VERSION\_NUMBER(3,2,4)
+     is equal to 1030241000.
 \end{description}
  
 \noindent \leda\ defines a macro \texttt{\_\_LEDA\_\_}

Installation/include/CGAL/config.h

@@ -42,6 +42,10 @@
 #  error "This compiler does not have a working STL"
 #endif
 
+// This macro computes the version number from an x.y.z release number.
+// It only works for public releases.
+#define CGAL_VERSION_NUMBER(x,y,z) (1000001 + 10000*x + 100*y + 10*z) * 1000
+
 #define CGAL_BEGIN_NAMESPACE namespace CGAL {
 #define CGAL_END_NAMESPACE }