added PDF/A-1b compliancy to all PDF export functions

for more details about this look at: https://www.kdab.com/creating-pdfa-documents-qt/

src/Gui/ApplicationPy.cpp

@@ -707,6 +707,8 @@ PyObject* Application::sExport(PyObject * /*self*/, PyObject *args)
                     if (view3d)
                         view3d->viewAll();
                     QPrinter printer(QPrinter::ScreenResolution);
+                    // setPdfVersion sets the printied PDF Version to comply with PDF/A-1b, more details under: https://www.kdab.com/creating-pdfa-documents-qt/
+                    printer.setPdfVersion(QPagedPaintDevice::PdfVersion_A1b);
                     printer.setOutputFormat(QPrinter::PdfFormat);
                     printer.setOutputFileName(fileName);
                     view->print(&printer);