UI: Do not store prop. view string data as QString

The internal data of a property value would be converted to QString and
Qt would inevitably try to convert the characters to another encoding,
causing the internal data to possibly become invalid.  Instead, use
QByteArray to treat it as nothing more than a byte array.

obs/properties-view.cpp

@@ -401,7 +401,7 @@ static void AddComboItem(QComboBox *combo, obs_property_t *prop,
 		var = QVariant::fromValue<double>(val);
 
 	} else if (format == OBS_COMBO_FORMAT_STRING) {
-		var = obs_property_list_item_string(prop, idx);
+		var = QByteArray(obs_property_list_item_string(prop, idx));
 	}
 
 	combo->addItem(QT_UTF8(name), var);
@@ -475,10 +475,11 @@ QWidget *OBSPropertiesView::AddList(obs_property_t *prop, bool &warning)
 	string value = from_obs_data(settings, name, format);
 
 	if (format == OBS_COMBO_FORMAT_STRING &&
-			type == OBS_COMBO_TYPE_EDITABLE)
+			type == OBS_COMBO_TYPE_EDITABLE) {
 		combo->lineEdit()->setText(QT_UTF8(value.c_str()));
-	else
-		idx = combo->findData(QT_UTF8(value.c_str()));
+	} else {
+		idx = combo->findData(QByteArray(value.c_str()));
+	}
 
 	if (type == OBS_COMBO_TYPE_EDITABLE)
 		return NewWidget(prop, combo,
@@ -1520,7 +1521,7 @@ void WidgetInfo::ListChanged(const char *setting)
 	QVariant         data;
 
 	if (type == OBS_COMBO_TYPE_EDITABLE) {
-		data = combo->currentText();
+		data = combo->currentText().toUtf8();
 	} else {
 		int index = combo->currentIndex();
 		if (index != -1)
@@ -1542,7 +1543,7 @@ void WidgetInfo::ListChanged(const char *setting)
 		break;
 	case OBS_COMBO_FORMAT_STRING:
 		obs_data_set_string(view->settings, setting,
-				QT_TO_UTF8(data.toString()));
+				data.toByteArray().constData());
 		break;
 	}
 }