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/Gui/ReportView.cpp

@@ -240,6 +240,7 @@ private:
  */
 
 ReportOutputObserver::ReportOutputObserver(ReportOutput *report)
+  : QObject(report)
 {
     this->reportView = report;
 }