use deck name as default file name for saving

cockatrice/src/window_deckeditor.cpp

@@ -320,6 +320,7 @@ bool WndDeckEditor::actSaveDeckAs()
 	dialog.setConfirmOverwrite(true);
 	dialog.setDefaultSuffix("cod");
 	dialog.setNameFilters(DeckList::fileNameFilters);
+	dialog.selectFile(deckModel->getDeckList()->getName());
 	if (!dialog.exec())
 		return false;