Change the variable name in function MainWindow::saveModel (arquivo_dlg to file_dlg).
Revert "Change the variable name in function MainWindow::saveModel (arquivo_dlg to file_dlg)."

This reverts commit 60f139002ecd44651502dfb672d77e7e2eab2540.
Change the variable name in function MainWindow::saveModel (arquivo_dlg to file_dlg).