Add std_auto_ptr.i defining typemaps for returning std::auto_ptr<>.

These typemaps are currently defined for C#, Java and Python only and the
tests are provided only for these languages.

Also add a brief description of the new header to the documentation.

Lib/python/std_auto_ptr.i

@@ -0,0 +1,17 @@
+/*
+    The typemaps here allow to handle functions returning std::auto_ptr<>,
+    which is the most common use of this type. If you have functions taking it
+    as parameter, these typemaps can't be used for them and you need to do
+    something else (e.g. use shared_ptr<> which SWIG supports fully).
+ */
+
+%define %auto_ptr(TYPE)
+%typemap (out) std::auto_ptr<TYPE > %{
+   %set_output(SWIG_NewPointerObj($1.release(), $descriptor(TYPE *), SWIG_POINTER_OWN | %newpointer_flags));
+%}
+%template() std::auto_ptr<TYPE >;
+%enddef
+
+namespace std {
+   template <class T> class auto_ptr {};
+}