App/Gui: fix memory leaks:

+ add function to cleanup units and quantities in debug build
+ fix reference leak in PropertyVector::getPyPathValue()
+ fix reference leak in PropertyPlacement::getPyPathValue()
+ in InterpreterSingleton::init() use a static std::vector<wchar_t*> instead of a C array
  to free memory at program end
+ in MainWindow::closeEvent() explicitly delete all task watchers
+ in ReportOutputObserver constructor pass parent to QObject
+ in PropertyEditor destructor explicitly delete QItemEditorFactory

src/App/Application.cpp

@@ -340,7 +340,6 @@ Application::Application(std::map<std::string,std::string> &mConfig)
 
     // Translate module
     PyObject* pTranslateModule = (new Base::Translate)->module().ptr();
-    Py_INCREF(pTranslateModule);
     PyModule_AddObject(pAppModule, "Qt", pTranslateModule);
 
     //insert Units module
@@ -1499,6 +1498,23 @@ int Application::_argc;
 char ** Application::_argv;
 
 
+void Application::cleanupUnits()
+{
+    try {
+        Base::PyGILStateLocker lock;
+        Py::Module mod (Py::Module("FreeCAD").getAttr("Units").ptr());
+
+        Py::List attr(mod.dir());
+        for (Py::List::iterator it = attr.begin(); it != attr.end(); ++it) {
+            mod.delAttr(Py::String(*it));
+        }
+    }
+    catch (Py::Exception& e) {
+        Base::PyGILStateLocker lock;
+        e.clear();
+    }
+}
+
 void Application::destruct(void)
 {
     // saving system parameter
@@ -1529,6 +1545,11 @@ void Application::destruct(void)
     _pcSysParamMngr = 0;
     _pcUserParamMngr = 0;
 
+#ifdef FC_DEBUG
+    // Do this only in debug mode for memory leak checkers
+    cleanupUnits();
+#endif
+
     // not initialized or double destruct!
     assert(_pcSingleton);
     delete _pcSingleton;