Copy description when DnD variables from Globals in resources and configuration variable panels to POUs. Also prevent making exception in case some other DropSource wouldn't provide description.
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# This file is part of Beremiz
# Copyright (C) 2019: Edouard TISSERANT
#
# See COPYING file for copyrights details.
from __future__ import absolute_import
from svghmi.svghmi import *