Add std::unique support

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

Closes #1722

Lib/java/std_unique_ptr.i

@@ -0,0 +1,29 @@
+/* -----------------------------------------------------------------------------
+ * 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 (jni) std::unique_ptr< TYPE > "jlong"
+%typemap (jtype) std::unique_ptr< TYPE > "long"
+%typemap (jstype) std::unique_ptr< TYPE > "$typemap(jstype, TYPE)"
+
+%typemap (out) std::unique_ptr< TYPE > %{
+   jlong lpp = 0;
+   *(TYPE **) &lpp = $1.release();
+   $result = lpp;
+%}
+%typemap(javaout) std::unique_ptr< TYPE > {
+     long cPtr = $jnicall;
+     return (cPtr == 0) ? null : new $typemap(jstype, TYPE)(cPtr, true);
+   }
+%template() std::unique_ptr< TYPE >;
+%enddef
+
+namespace std {
+   template <class T> class unique_ptr {};
+}