SVGHMI: Changes /CURRENT_PAGE_* behaviour to prevent problem whith multiclient : all clients were switching page when one was jumping.
- now PLC have to prefix page name with "!" to order page switch.
- HMI do not prefix with "!" when jumping, this avoiding looping incidently
- In case of multiple client:
CURRENT_PAGE reflects current page of last client hwo did jump
Setting CURRENT_PAGE with "!" affects all clients simultaneously

# opcua/__init__.py

from __future__ import absolute_import

from .client import OPCUAClient

# class RootClass(object):
#     XSD = """<?xml version="1.0" encoding="ISO-8859-1" ?>
#     <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
#     </xsd:schema>
#     """
#     CTNChildrenTypes = [("OPCUAClient", OPCUAClient, "OPCUA Client")]
#