Add OPC-UA simple synchronous client extension.

This extension uses python-opcua to growse server nodes, and generates runtime C code that use open62541.
- python-opcua must be available in python path (i.e. "import opcua" must succeed). Can be installed from pypi with "python2 -m pip install opcua --user" .
- at build time, open62541 is expected to be build in "open62541" directory, aside "beremiz" directory.

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# See COPYING.Runtime file for copyrights details.

LogLevels = ["CRITICAL", "WARNING", "INFO", "DEBUG"]
LogLevelsCount = len(LogLevels)
LogLevelsDict = dict(zip(LogLevels, range(LogLevelsCount)))
LogLevelsDefault = LogLevelsDict["DEBUG"]