Button, ToggleButton and slider updated. Error to warning when building

Button fixed so it doesn't release until it gets feedback from plc

Toggle button changed so it makes changes instantly. There was too big delay if we waited for feedback.

Slider added new features need some changes for final version.

#!/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 *