Add std::unique support

Simple copy of current auto_ptr support (just suppport for
functions returning std::unique_ptr).

Closes #1722

Lib/python/std_unique_ptr.i

@@ -0,0 +1,19 @@
+/* -----------------------------------------------------------------------------
+ * std_unique_ptr.i
+ *
+ * The typemaps here allow handling functions returning std::unique_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 %unique_ptr(TYPE)
+%typemap (out) std::unique_ptr< TYPE > %{
+   %set_output(SWIG_NewPointerObj($1.release(), $descriptor(TYPE *), SWIG_POINTER_OWN | %newpointer_flags));
+%}
+%template() std::unique_ptr< TYPE >;
+%enddef
+
+namespace std {
+   template <class T> class unique_ptr {};
+}